Chapter 15 Water and Waste System

Standardized Technical Specification
PRIIA 305 Next-Generation Equipment Committee
Bi-Level Passenger Rail Cars
Chapter 15
Water and Waste System
Table of Contents
15-1
Table of Contents
15.0 Water and Waste System ......................................................................................... 15-2 15.1 Overview ............................................................................................................. 15-2 15.2 General Requirements ......................................................................................... 15-2 15.2.1 Water System Features .................................................................................. 15-2 15.2.2 Waste System Features ................................................................................. 15-3 15.2.3 FDA Compliance ............................................................................................ 15-3 15.3 Water System ...................................................................................................... 15-4 15.3.1 Water Tank ................................................................................................... 15-4 15.3.2 Water Fill, Vent and Drain System................................................................. 15-4 15.3.3 Pressurization System ................................................................................... 15-4 15.3.4 Distribution and Piping ................................................................................. 15-5 15.3.5 Pressure Regulators ...................................................................................... 15-5 15.3.6 Backflow Preventers/Vacuum Breakers ......................................................... 15-5 15.3.7 Sink, Faucet and Drain ................................................................................. 15-5 15.3.8 Water Heaters ............................................................................................... 15-5 15.3.9 Water Cooler and Alcove ................................................................................ 15-6 15.3.10 Toilet Flush Water ......................................................................................... 15-6 15.3.11 Waste Tank Rinse Water ................................................................................ 15-6 15.3.12 Galley Water .................................................................................................. 15-6 15.4 Waste System...................................................................................................... 15-6 15.4.1 Operation ...................................................................................................... 15-7 15.4.2 Toilet Bowl with Flush Control ...................................................................... 15-8 15.4.3 Waste Tank and Vacuum System .................................................................. 15-9 15.4.4 Waste Tank Draining and Rinsing ............................................................... 15-11 15.4.5 Vent ............................................................................................................ 15-11 15.4.6 Sink drains ................................................................................................. 15-11 15.4.7 Piping .......................................................................................................... 15-12 15.4.8 Indicators .................................................................................................... 15-12 15.5 Freeze Protection ............................................................................................... 15-13 15.5.1 Blanket Heaters........................................................................................... 15-13 15.5.2 Heat Tape .................................................................................................... 15-13 15.5.3 Automatic Drain Valves ............................................................................... 15-13 Water and Waste System
15.0
Water and Waste System
15.1
Overview
15-2
A pressurized fresh water system shall be provided on each car to supply potable water for
drinking, hand washing, toilet flushing and Café car galley requirements. Storage for 200 gal
(757 L) of potable water shall be located in the A/F-end or B-end equipment room of coach and
cab/baggage cars, and 300 gal (1135 L) on café/lounge cars. A re-circulating chiller shall
provide chilled potable water to two dispensing stations, one on each level of all cars.
A vacuum type waste retention system shall be provided on each car. The waste tank, drain
lines and associated components shall be located in the B-end equipment room. Gray water
from toilet room and galley hand washing sinks shall be captured and pumped to the waste
retention tank.
No waste water shall be permitted to drain to ground, including gray water from hand washing
sinks. Only fresh water from the following sources shall be permitted to drain to ground:
•
•
•
•
•
Condensate from Heating, Ventilation and Air Conditioning (HVAC) and chiller units
Drain from potable water chillers
Melt water from ice storage bins
Carbody drains from door tracks and equipment rooms
Fresh water from water supply system when drained manually or by freeze protection
devices
All car types shall have an Accessible Toilet Room (ATR) on the lower level.
cab/baggage cars shall also have a Unisex Toilet Room (UTR) on the upper level.
Coaches and
The water and waste systems shall be protected from damage due to freezing through the use
of heat tape, blanket heaters, automatic drain valves (water system only) and insulation.
See Chapter 14, Food Service, for galley water system requirements.
15.2
General Requirements
15.2.1
Water System Features
A potable water supply system shall be provided on each car to supply water for drinking,
washing, cleaning and waste disposal. The fresh water shall be supplied from one or more
storage tanks located in the A/F-end equipment room. These water tanks shall be filled from a
water fill valve located on each side of the car at the A/F-end.
The basic features of the water system include:
•
•
•
•
•
•
•
•
200 gal (757 L) fresh water storage in coach and cab/baggage cars, 300 gal (1136 L) in
café/lounge cars (one or more tanks)
Water fill, vent and drain system
Pressurization system
Distribution and piping
Pressure regulators
Backflow or vacuum preventers
Sinks, faucets and drains
Water heaters (or flash heaters)
Water and Waste System
•
•
•
•
15.2.2
15-3
Water cooler and alcove
Fresh water for toilet bowl rinse during flush
Fresh water for waste retention tank rinse during draining
Galley water: sinks and coffee maker
Waste System Features
A waste system shall provide flush toilets in each toilet room. The waste system shall be a
vacuum system with sufficient capacity to collect and retain a minimum of 250 gal (946 L) of
passenger waste, in a single tank, for discharge at a dumping facility. Waste incineration is
not permitted. The waste system shall be designed with a minimum service life of 30 years, a
minimum overhaul cycle of eight years and a minimum maintenance cycle of one year.
Overhauling of waste system components may be included in the maintenance cycle.
Recommended waste system components included in maintenance cycle is to be approved by
the Customer. The waste system and all its components shall be designed for fail-safe
operation and protection of passengers, service personnel and equipment.
The waste tank shall be located in the B-end equipment room, and shall have waste discharge
drain lines and valves located adjacent to the tank on each side of the car.
The waste system shall be designed to operate normally at all elevations from 200 ft (61 m)
below to 9,200 ft (2806 m) above sea level, and under all environmental and operational
conditions identified in PRIIA Specification 305-912.
Toilet flushing shall be inhibited due to: lack of adequate water, air pressure, vacuum or
electric power; waste tank full or waste drain valve open.
The basic features of the waste system include:
•
•
•
•
•
•
•
15.2.3
Toilet bowl with flush control
250 gal (946 L) usable waste tank capacity
Vacuum source and control
Waste tank vent
System status indicators
Waste tank drain and rinse
Piping
FDA Compliance
The Contractor shall arrange for an FDA inspection of the design and installation of the water
and waste system on each car to certify that it meets all requirements. Documentation of
compliance shall be included in each vehicle’s history book.
CDRL
Water from hand washing faucets shall be dispensed at a temperature between 100°F (37.7°C)
and 108°F (42.2°C), in accordance with FDA/PHS requirements. All water heaters and flash
heaters shall maintain water temperature in accordance with FDA/PHS regulations.
FDA-approved backflow preventers shall be located as necessary to prevent contamination of
the fresh water system from the waste system. Backflow preventers shall be easily accessible
for inspection and maintenance.
The Contractor shall thoroughly clean and sanitize the fresh water system on each vehicle prior
to release from the Contractor’s facility, to remove dirt, debris, solder, adhesive, cleaning
agents or other contaminants from the manufacturing process. All filters in the fresh water
system shall be renewed after the sanitization process and before release of the vehicle.
Water and Waste System
15.3
Water System
15.3.1
Water Tank
15-4
Storage for 200 gal (757 L) of potable water shall be provided on coach and cab/baggage cars,
and 300 gal (1136 L) on café/lounge cars, in one or more stainless steel tanks located in the
A/F-end equipment room. Water tanks shall include internal baffle plates to minimize wave
action produced by train motion. Water storage tanks shall comply with the latest edition of
the ASME Boiler and Pressure Vessel Code sections IX and X.
Tanks shall be equipped with a manual drain valve for use in tank sanitizing as required by the
FDA. Manual drain valves shall be readily accessible within the equipment room and shall
drain to ground.
15.3.2
Water Fill, Vent and Drain System
A water fill point shall be provided on each side of the car. The fill point and three-way valve
shall be enclosed in a stainless steel box inset into the equipment room and equipped with a
weather-tight cover. The water fill box cover shall be spring loaded to be held securely in the
closed position, with a strut or latch to hold the cover in the open position during water filling.
The water fill point shall be a nozzle (Equipment Hydraulique Rainville p/n H-G15-001X or
equivalent) enclosed in a metal shroud (Clements National p/n MRA-H-ALST-V109 or
equivalent) and be painted medium blue.
A three-way valve (NYAB p/n 705504 N-9723 or equivalent) shall be provided on each side of
the car that will cut off pressurization air and vent the water tanks when placed in the FILL
position. This will allow the tank to be filled via a check valve located immediately behind the
fill nozzle. The three-way valve shall be enclosed behind sheet metal, serviceable from the
front, with only the operating handle exposed. When venting the tanks, vented air shall blow
downwards to the ground and away from maintenance personnel operating the valve.
When the valve is placed in the WATER position, the vent will be closed and air pressure applied
to the water in the tanks. Valves and piping shall be sized for a maximum fill time of 15
minutes, including the time necessary to vent the tank.
Water fill point piping and valves shall be insulated and equipped with heat tape for freeze
protection. All hardware used in the water fill system shall be corrosion resistant and rated for
use in a wet environment.
15.3.3
Pressurization System
The water supply system shall be pressurized through the use of auxiliary air, provided from
the main reservoir through a governor and regulator valve. Air pressure for water rising shall
be set for 45.0 psig (3.1 bar g) ± 2.0 psig (0.1 bar g). The system shall be designed such that
water shall not flow back into the auxiliary air system under any circumstances.
A desiccant air filter shall be provided on the main reservoir air supply line to remove
contaminates from water raising air (see Chapter 7).
Potable water shall be provided through a pressure reduction valve at 20.0 psig (1.4 bar g) ±
2.0 psig (0.1 bar g) for hand washing sinks in toilet rooms, potable water drinking fountains
and café galley sinks.
Water for toilet bowl rinse shall be provided at 28.0 psig (1.9 bar g) ± 2.0 psig (0.1 bar g).
Waste tank rinse water shall be unregulated.
Water and Waste System
15.3.4
15-5
Distribution and Piping
Distribution piping shall be seamless stainless steel tubing in the longest possible continuous
length without joints, with stainless steel fittings. Anti-water hammer air chambers shall be
provided as required. Easily accessible ball cock type isolation valves shall be provided for
each of the following (located upstream of pressure regulators, backflow preventers, etc):
•
•
•
•
•
•
•
Main water supply (at water tanks)
Sinks (combined hot and cold water feed at faucet)
Water chiller
Toilet flush (one for each toilet)
Waste tank rinse
Galley sinks and coffee maker
Water heaters
Easily accessible manual drain valves shall be provided to allow draining water from the car as
well as to service equipment.
Engraved color coded laminated plastic tags, attached to piping, will be provided to identify all
water and air pressure regulators, water and waste cutout cocks, and drain cocks.
15.3.5
Pressure Regulators
Pressure regulators, complete with integral gauge shall be supplied to maintain the water
pressures identified herein. Regulators shall be adjustable and have a locking ring or other
locking device to prevent unintended changes to pressure settings.
15.3.6
Backflow Preventers/Vacuum Breakers
The potable water system shall be isolated from toilet flush water and toilet waste tank rinse
water through the use of FDA-approved backflow preventers or vacuum breakers. Backflow
preventers/vacuum breakers shall be located for easy access and replacement.
15.3.7
Sink, Faucet and Drain
Each toilet room shall be equipped with a sink, faucet and drain. All sinks shall be stainless
steel. All gray water discharge from the sinks shall be captured and sent to the waste tank.
Minimum drain line internal diameter shall be 1.5 in. (38.1 mm). Drain water may not be used
as flush water for toilets.
Sink faucets shall utilize an automatic start-stop feature, such as infrared or proximity sensor,
that will permit hands-free use of the faucet. The sensor may be mounted in the counter
surface or the faucet. Faucets shall be regulated to have a flow rate of no more than 0.5 gpm
(1.9 L/min), in order to maintain FDA-compliant water temperature.
15.3.8
Water Heaters
Each restroom shall be equipped with a standard one-gallon, 120VAC, 1250 W (minimum),
vertical unit. Hot water temperature in the tank shall be maintained in accordance with PHS
recommendations, and shall be mixed with cold water at the toilet room faucet to maintain
hand washing water temperature between 100°F (37.7°C) and 108°F (42.2°C) at a flow rate of
0.5 gpm (1.9 L/min), in accordance with FDA/PHS regulations. The water heaters shall
include the following features: immersion heater, factory installed thermostatic control and low
water protection. The tank relief valve shall be set at 75.0 psig (5.2 bar g). The water feed
piping to the heater shall be from the bottom to allow gravity draining from the local freeze
protection valve. The water heater shall be easily accessible and removable without disturbing
Water and Waste System
15-6
any other equipment. Water heaters shall conform to ASME Boiler and Pressure Vessel Code
sections IX and X.
For galley water heater, refer to Chapter 14.
15.3.8.1
Instant-Flow Water Heaters (Flash Heaters)
An in-line instant-flow water heater (flash heater) may be provided as an alternate to a
standard water heater. The flash heater shall meet temperature requirements of the water
heater, and must be able to increase water temperature from an ambient temperature of no
more than 50°F (10°C) to the FDA required 100°F (37.7°C) to 108°F (42.2°C) at a flow rate of no
less than 0.5 gpm (1.9 L/min).
The flash heaters shall be flow activated and shall operate at 120VAC. Flash heaters shall be
easily accessible for replacement or maintenance.
15.3.9
Water Cooler and Alcove
Each drinking water station shall consist of a stainless steel alcove equipped with a chilled
water dispenser and drain. The drain shall be 0.5 in. (12.7 mm) copper piping and shall drain
to ground under the car. A kazoo shall be installed on the end of the drain under the car.
Water coolers shall be capable of producing at least 10 gal (38 L) of chilled water per hour to
spigots at designated locations on the upper and lower levels of all cars. The water cooler shall
be capable of chilling water from 80°F (26.6°C) to 50°F (10°C) within 10 minutes. The chilled
water shall be re-circulated to provide chilled water on demand.
Water coolers shall operate from 120VAC and shall use a non-ozone-depleting refrigerant
meeting 40CFR Part 82. The water cooler shall have an FDA-approved particulate and bacteria
filter on the supply line to the spigot.
Water shall be dispensed at a rate no greater than 0.5 gpm (1.9 L/min), or by gravity, to
minimize spraying.
15.3.10
Toilet Flush Water
Toilet flush water shall be provided to the toilet bowl assembly through a cutout cock, pressure
regulator and backflow preventer.
15.3.11
Waste Tank Rinse Water
Waste tank rinse water shall be provided to the waste tank through a cutout cock and backflow
preventer. Waste tank rinse water shall be at the same pressure as the water raising system.
15.3.12
Galley Water
Potable water shall be provided to the galley of the café/lounge cars for hand washing, food
preparation and coffee makers. See Chapter 14 for details.
15.4
Waste System
A waste system shall be provided on each car. The system shall have a useful waste storage
capacity of at least 250 gal (946 L). The waste system shall be comprised of vacuum toilets,
constant-vacuum waste transfer system, a central waste collection tank, two external waste
valve stations, indicator panels and associated piping and controls,
Safety, reliability and ease of servicing and maintenance shall be major design considerations.
The system shall be designed and tested to operate at all elevations from 200 ft (61 m) below to
9,200 ft (2806 m) above sea level, in accordance with PRIIA Specification 305-912.
Water and Waste System
15-7
Pump motors shall operate from 480VAC, 3-phase, 60 Hz head end power. All controls,
solenoid valves, relays and circuitry, and antifreeze protection shall operate from 120VAC, 60
Hz. All transducers and indicator devices shall operate from 74VDC.
The equipment shall be designed for a minimum service life of 30 years, a minimum overhaul
cycle of eight years and a minimum maintenance and level sensor calibration cycle of no less
than one year.
The system shall consist of the assemblies listed below:
•
•
•
•
Vacuum toilet
Waste collection tank
Waste valve stations
Waste system indicator panels
The system shall have no adjustments and automatically recover from loss of power, air or
water pressure when restored. The system shall have a manual reset pushbutton provided on
the status panel to reset the system after a lockout, such as resulting from a toilet with a failed
open vacuum flush valve. Cycling the 74VDC circuit breaker shall also reset the system.
Gray water from hand washing sinks shall be collected and stored in the waste tank. Gray
water may be transferred from sinks to waste tank by the use of pumps or vacuum draw. Gray
water shall not drain to ground.
15.4.1
Operation
A flush cycle shall be initiated by operating a flush actuating pushbutton located adjacent to
the raised toilet lid in the UTR. The ATR will have two flush pushbuttons, one located on each
side of the toilet, per ADA requirements. The flush function at all other toilets in the car will be
disabled during the flush cycle. The vacuum blower shall automatically come on at the
beginning of the cycle. Pressurized rinse water shall be sprayed into the toilet bowl before
waste is evacuated. Toilet operation shall be disabled when: there is inadequate water,
vacuum, air pressure or 480VAC; the waste tank is full; or when the waste tank drain line is
open.
The waste shall be drawn, by vacuum, from each toilet in the car and transported through a
2 in. (51 mm) diameter waste line to a holding tank for discharge at a collection facility. The
holding tank shall be continuously under vacuum, regulated by blower operation and
maintained by an air-tight check valve between the tank and vacuum blower.
Indicators shall show the volume of waste collected in the retention tank and system status.
The vacuum blower and toilet flushing shall be disabled whenever waste volume collected
exceeds usable tank capacity.
A waste discharge valve shall be located on each side of the car near the B-end truck to drain
the waste collection tank. Waste may be drained from the retention tank by gravity or vacuum
assistance from the servicing facility. When the waste discharge valve is opened: vacuum
blower operation will be disabled; the waste retention tank will be vented; the interior of the
retention tank will be rinsed with wayside water; and wastes will be drained from the retention
tank to the servicing facility. Draining the waste tank shall not require more than one person.
Servicing time for draining the tank shall not exceed five minutes. The waste tank must be
able to be drained without requiring 480VAC power or air pressure to be present on the car.
An external rinse water hookup shall be provided if rinse water is required for draining.
Water and Waste System
15.4.2
15-8
Toilet Bowl with Flush Control
Each toilet room of each car shall be equipped with a toilet stand and shroud.
The toilet assembly shall be a self-contained, free standing unit consisting of a bowl with spray
ring, rinse valve, drain valve, electronic flush control module, isolation valve, and supporting
frame. The assembly shall be mounted on a stainless steel pan, to contain flooding should the
outlet become blocked.
A flush pushbutton shall be provided to initiate the flush cycle. Pressurized rinse water shall
be sprayed into the toilet bowl before waste is evacuated. Force required to activate the flush
pushbutton shall be within ADA requirements.
Pressurized rinse water, 7 oz (198 g) to 8 oz (227 g) per flush, shall be sprayed into the toilet
bowl before waste is evacuated. It shall be provided from the car water system via a dedicated
local cutout cock, backflow preventer and pressure regulator.
Compressed air from the main reservoir shall be provided via a cutout cock and pressure
regulator to operate the toilet flush valve.
The toilet assembly shall be mounted so as to be easily accessible and removable for service
and maintenance. The shroud shall be secured with captive fasteners so as to be easily
removed and installed. Likewise, valves shall be easily accessible, without tools, for operation
from inside the car.
15.4.2.1
Toilet Bowl
The toilet bowl shall be stainless steel with a non-stick coating (such as Teflon), applied inside
to prevent waste matter and mineral deposits from adhering. Bowl surfaces shall curve in a
continuous fashion and shall be free of recesses and inaccessible areas. The sides of the bowl
shall be steep and sloped toward the vacuum vent inlet to allow waste to accumulate for
evacuation. To prevent blockage of the sewage system, the outlet of the bowl shall be a
maximum 1.75 in. (44.45 mm) in diameter and shall be the most restrictive point in the piping
system. The bowl and spray ring shall be easily and completely cleaned with ordinary
cleansing agents and tools.
15.4.2.2
Overflow Pan
A pan shall form part of the interior bathroom assembly. The floor pan of the modules shall be
FRP with a stainless steel overflow pan under the toilet bowl. The purpose is to prevent fluids
from wicking beneath the toilet room flooring, both for hygiene and also to prevent degradation
of the subflooring materials. This overflow pan shall be watertight and have raised edges of at
least 2 in. (51 mm) in height. The pan’s exposed edges shall be folded for safety and to provide
stiffness. The floor pan shall be installed over, and attached to, the subfloor of the car.
Attachment points shall be on the sides, rather than the bottom surface, and be watertight.
A drain tube shall penetrate the floor of the pan to allow spilled fluids to drain to ground. The
drain shall be flush with the bottom of the pan, and shall extend through to the underside of
the car. It shall be sealed to make the joint waterproof and shall also be sealed with an
appropriate material to prevent flame propagation from underfloor flame sources. A split
rubber hose (kazoo) shall be attached to the bottom end of the drain tube to prevent dust and
debris from being blown up the tube.
15.4.2.3
Flush Valve
The flush valve shall be either pneumatically operated (60.0 psig [4.1 bar g]-120.0 psig [8.3
bar g]), or vacuum operated (3-12 in. of Hg), and be a self-contained unit which provides a
zero-leakage seal at the bowl outlet after operation. Operation shall be initiated through a
Water and Waste System
15-9
solenoid valve. The flush valve shall seal within 0.1 seconds from a full open position. The
zero-leakage seal shall be maintained under 15 in. Hg (51 kPa) of vacuum. The valve shall be
constructed entirely of stainless steel with the exception of seals and actuator. All surfaces
that are subject to wear shall be designed to be self-lubricating with no maintenance required.
Seals shall be easily replaced with standard tools.
The flush valve shall pass a Customer approved proof-of-design test, which shall be included in
the vehicle’s proof-of-design test plan, with a minimum of 300,000 cycles of operation. See
Chapter 19.
15.4.2.4
Rinse Valve
The rinse valve shall control rinse water flow into the bowl. The valve shall be designed to
maximize water pressure for water flow and orifice size when activated and provide a positive
zero-leak seal when closed.
15.4.2.5
Electronic Flush Control
The electronic flush control unit shall control all toilet operations and activate the blower when
the flush cycle is initiated. All electrical connections between the car and toilet assembly shall
be made through a multi-pin connector. The electronic module shall plug into a card socket.
The flush cycle shall be initiated at each toilet by a flush pushbutton. The flush cycle shall be
delayed whenever another flush cycle on another toilet on the car is in progress. The control
unit will provide the following timing functions:
•
•
•
Blower ON signal from flush initiation;
1.0-1.5 second RINSE activated 0.5-0.7 seconds from flush initiation; and
3.0-3.5 second DRAIN activated 1.0-1.5 seconds from flush initiation.
15.4.2.6
Flush Pushbutton
At least one clearly labeled flush pushbutton shall be provided in the UTR, and two flush
buttons in the ATR to initiate the flush cycle.
15.4.2.7
Cut Out Valve
A rinse water and air cut out valve shall be provided for each toilet assembly. Cut out valves
shall be easily accessible, without tools, for operation en route from inside the car. Pipe flanges
and couplers shall be provided to allow easy and quick removal of the toilet assembly by
maintenance personnel.
15.4.2.8
Vacuum Isolation Valve
A slide type waste line vacuum isolation valve shall be provided on the toilet assembly with
actuator handle accessible from the front of the toilet at floor level.
15.4.3
Waste Tank and Vacuum System
The waste tank assembly shall be designed as a self-contained unit suitable for mounting in an
equipment room. The assembly shall consist of the retention tank, vacuum blower, level
measuring system, tank drainage, freeze protection, electronic controls and debris shields.
Pump motors shall operate from 480VAC, 3-phase, 60 Hz HEP. All controls, solenoid valves,
relays and circuitry, and antifreeze protection shall operate from 120VAC, 60 Hz. All
transducers and indicator devices shall operate from 74VDC.
Water and Waste System
15.4.3.1
15-10
Retention Tank
The Waste Collection Tank assembly shall be a self-contained pallet-type unit intended for
mounting in the car equipment room. The assembly shall consist of the retention tank,
vacuum blower, check valve, vacuum relief valves, level indicators, level-measuring system,
rinse valve, freeze protection and electrical control panel. Equipment location in the equipment
room shall allow the unit to be easily serviced in place for most repairs, including replacing the
vacuum blower. Design shall have the vacuum blower and associated check valve located on
the exposed side to the tank when it is mounted in the equipment room, to allow these
components to be easily serviced. In addition, it shall be easy to remove the unit from the car
for preventative maintenance and overhaul. This includes not having to move or remove any
equipment not directly related to the waste system.
Usable retention tank capacity shall be a minimum 250 gal (946 L).
The waste holding tank will be made of carbon steel. The interior and exterior surfaces will be
coated with a corrosion resistant epoxy powder finish. This coating shall provide a tank life in
excess of 30 years.
Self-cleaning sight glasses at the FULL, 2/3 and EMPTY levels shall be provided as a visual check
of the waste level. A removable clean-out cover large enough to permit the interior of the tank
to be cleaned and inspected shall be provided. A water separator located inside the tank shall
prevent water and waste from being ingested into the vacuum blower. A 28.0 psig (1.9 bar g) ±
2.0 psig (0.1 bar g) rinse shall automatically apply fresh rinse water at a rate of 3 gpm
(11 L/min) to 6 gpm (23 L/min) to the sides of the tank during the drain cycle. The rinse valve
shall be mechanically opened by the tank discharge actuator.
15.4.3.2
Central Control Panel
The control system for the overall waste system shall be incorporated onto the waste tank unit,
enclosed in a weather-tight electrical cabinet. The central control panel shall consist of
vacuum blower control and protection functions, level measuring, status panel interface,
vacuum switches, transformer, AC and DC circuit breakers, tank draining functions and safety
switch. All conduit connections to the control box shall be liquid-tight and shall use
waterproof fittings and hardware. All electrical connections between the car and tank
assembly shall be made through multi-pin connectors. The electronic module shall plug into a
card socket.
15.4.3.3
Vacuum Blower and Control
The waste collection system shall be a constant vacuum type, with the vacuum obtained from
an electrically operated blower operating on 480VAC. The vacuum blower will come on at the
beginning of the flush cycle and will cycle on as needed to maintain the required vacuum.
The vacuum blower shall be capable of producing a differential pressure of at least 12 in. Hg
(41 kPa) and a flow rate of at least 200 SCFM (6 Sm3/min). Tank vacuum shall be maintained
at 6-10 in. Hg (20-34 kPa) through operation of the blower and an air-tight check valve
between the tank and blower. The vacuum blower shall cycle on when the system differential
pressure falls below 6 in. Hg (20 kPa) and cycle OFF when the differential pressure rises above
10 in. Hg (34 kPa). A 19 to 21 second time-out function shall prevent continuous vacuum
blower operation at high altitudes. Any toilet FLUSH signal shall start the blower and restart
the time-out function. The blower shall remain off whenever the tank is full, or during the tank
drain cycle.
Water and Waste System
15.4.3.4
15-11
Tank Level Measuring System
A load-cell tank level measuring system shall be provided to monitor the level of waste inside
the retention tank. An input shall be provided to the status panel inside the car to indicate
when the tank is empty, 2/3 full, and full. An input shall be provided to the vacuum blower
control whenever the tank is full, which then sets the toilet room light to OUT OF SERVICE and
displays TANK FULL on the system status panel.
The sensors, measurement system and TANK EMPTY indicator lights shall operate from the car
74VDC power source and shall draw no more than 1 amp of current at nominal voltage. For
the level measuring system, the tank shall be considered "empty" when it contains less than
5 gal (19 L) of waste.
15.4.4
Waste Tank Draining and Rinsing
Tank drainage shall be through a 4 in. (102 mm) stainless steel or epoxy-coated malleable-iron
discharge line. A 4 in. (102 mm) inside diameter full port ball-type waste discharge valve, fitted
with an Andrews quick disconnect fitting for interface with the servicing facility shall be
provided on each side of the car. Tank drainage shall be controlled by a manually operated
drain valve. When operated, the drain valve shall: vent the tank, open the tank rinse valve,
deactivate the vacuum blower and drain the tank.
A waterproof waste valve station, enclosing the discharge valve and associated items shall be
provided beneath the car on each side of the B-end. All sheet metal and related hardware shall
be 304 stainless steel to inhibit corrosion. Heat tape shall be applied to the valve and piping
with the use of aluminum heat transfer tape, and the surrounding space well insulated with a
durable waterproof, thermal insulation. The valve operating handle shall be robust, painted
yellow and oriented so as to shield it from damage caused by debris impact. The valve closed
position is with the handle oriented vertically, pointing downward. To open the valve, the
handle shall be rotated 90 degrees towards the side of the car (away from the center of the car).
To close the valve, the handle shall be rotated 90 degrees downward.Waste may be drained
from the retention tank by gravity or vacuum assistance from the servicing facility. When the
waste discharge valve is opened: vacuum blower operation will be disabled; the waste retention
tank will be vented; the interior of the retention tank will be rinsed with on-board water; and
waste will be drained from the retention tank to the servicing facility. It may be possible to
drain the tank without requiring 480VAC power or compressed air on the car.
Time to drain a full tank using a gravity system shall not exceed five minutes. The tank shall
be considered empty when less than 5 gal (19 L) of waste remains in the tank. Accumulated
deposits shall not exceed 2% of tank volume over one year.
15.4.5
Vent
The vent from the waste tank blower shall be routed up to the roof level, terminating at a
louvered vent placed immediately below the roof line and on the opposite side from the HVAC
fresh air intake to prevent ingestion of waste exhaust vapors by the HVAC system. The vent
line shall run to a carbon filter located in an accessible box allowing for easy filter replacement.
A moisture drain shall be installed at the bottom of any vertical runs to permit the draining of
accumulated water.
15.4.6
Sink drains
Gray water from hand washing sinks in toilet rooms and galleys shall be captured and
transferred to the waste tank for storage and discharge at maintenance facilities. Gray water
shall not drain to ground. Gray water may be transferred from sinks to waste tank by pumps
or vacuum draw. Level sensing and water transfer equipment must be capable of maintaining
Water and Waste System
15-12
function while coated with soap scum. Sink tanks, pumps, vacuum valves and manual drains
shall be located in an easily accessible position for maintainability.
15.4.7
Piping
Water and air piping to the waste system shall be seamless stainless steel tubing in the longest
possible continuous length without joints, with stainless steel fittings. The waste line between
toilets and the waste tank shall be 2 in. (51 mm) (i.d.) non-metallic pipe that conforms to PRIIA
Specification 305-911. There shall be no sharp bends or moisture traps in the pipe routing.
All fresh water and waste piping shall have accessible drain ports for draining of the system
manually to prevent water freezing in the pipes. There shall be no low points in the water
supply or waste system that cannot be drained. Waste piping must not be drained to the
ground. The waste system must be dry flushed to produce an empty piping situation. Waste
in the retention tank must then be dumped using the normal procedure.
15.4.8
Indicators
The status of the waste system shall be monitored continuously and displayed on indicator
panels as described below. The power source for the indicator panels shall be 74VDC so that
the system status is displayed when there is no HEP.
A TANK EMPTY light (black front with green letters) shall be installed on the waste tank assembly
adjacent to each of the drain valves. The indicator shall be visible by maintenance personnel
so they will know when the tank is empty so that the discharge line may be disconnected.
15.4.8.1
Status Panel
A status panel shall be installed inside the electric locker, and on the waste tank control box in
the equipment room, to provide a visual indication of system status. The panel shall be black
front with letter color specified below. A PUSH TO TEST button shall be provided to test the lights
and reset the system.
The following indications shall be provided:
Label
Indicator
Function
TOILET SYSTEM
WHITE
System Identifier (Goes on together with any indicator below.)
POWER OFF
RED
HEP OFF to the waste system.
LOW AIR
RED
Less than 60.0 psig (4.1 bar g) of air pressure.
LOW WATER
YELLOW
Less than 15 psig (1 bar g) of water pressure.
LOW VACUUM
RED
Differential vacuum pressure is less than 3 in. Hg (10 kPa), except
when flush valve is open for toilet flush cycle.
FAULT
RED
Waste system failure detected.
TANK FULL
RED
Retention tank is full.
2/3 FULL
YELLOW
Retention tank is 2/3 full.
TANK EMPTY
GREEN
Retention tank is empty.
The white TOILET SYSTEM indicator lights shall be lit when any other indicator is on.
vacuum function shall be disabled when the flush valve is open for the flush cycle.
Low
A yellow LED indicator light shall be included on the system status panel on the electrical
locker wall in the vestibule. This indicator shall be on continuously when the system is
powered and operating normally, flashing when the system has a fault, and off when the
system is not powered. See Chapter 11 for details.
Water and Waste System
15-13
An LED TOILET OUT OF SERVICE indicator shall be provided outside each restroom to indicate to
passengers that the restroom is out of service when the toilet system is not functioning. See
Chapter 9 for details.
15.5
Freeze Protection
The water and waste system shall be freeze-protected to enable the car to be left off power
indefinitely in subfreezing temperatures with no damage resulting to any component of the
system under any condition.
Freeze protection consists of three separate functions:
•
•
•
Thermal insulation
Protective heat, which keeps various equipment warm in cold weather
Automatic drain valves, which drain water from car piping and tanks should a
prolonged loss of heat occur
The water and waste tank enclosures shall be thermally insulated to allow the protective heat
to keep the tanks from freezing at ambient temperatures down to -40°F (-40°C). The
installations shall be designed to remain waterproof and retain the insulation quality for the
life of the equipment.
Protective heat shall be installed on fresh water and waste storage equipment and piping within
the equipment room to maintain temperatures above freezing during these low ambient
conditions.
15.5.1
Blanket Heaters
Blanket heaters, operating on 120VAC, may be employed for heating the water and waste
tanks. Attached directly to the bottom of the respective tank, each of these heaters shall
include two integral thermostats, one to activate the heat when the tank temperature falls
below approximately 40°F (4.4°C) and opening at approximately 55°F (12.7°C), and a second,
providing a high limit function.
15.5.2
Heat Tape
Self-limiting heat tape, 120VAC, nominally 8 W per foot, shall be applied in areas subject to
freezing temperatures, such as:
•
•
•
•
Water piping
Waste piping
Water-fill housings
Waste drain piping and valves
The heat tape shall be installed in a way to permit pipes and fittings to be disassembled for
maintenance and repairs without removing the entire protective system.
The freeze protection thermostat will activate the heat tapes via a freeze protection contactor
when the ambient outside temperature falls below 40°F (4.4°C).
15.5.3
Automatic Drain Valves
Air-sensing automatic drain valves with heater shall be used to protect the fresh water system
from freezing should a loss of power and heat occurs. These valves include a heater on the
sensing element to rapidly warm the element when HEP is applied to the car to allow the valve
to close quickly after a power outage in cold weather. This allows a car to be watered shortly
Water and Waste System
15-14
after power is applied rather than waiting for the piping to be warmed by the car heating
system.
These valves shall be located at low points throughout the water system piping to allow all car
water to drain automatically should the car lose power and the ambient air temperature fall
below 38°F (3.3°C) at the valve. No water shall be trapped in low points of the system.
Vacuum relief valves are also required to allow the draining to occur. Potable and non-potable
water shall use separate valves. Fresh water shall only be drained from the car when ambient
outside temperatures are below 38°F (3.3°C) and the car has no HEP or layover power.
The waste system shall not use automatic drain valves. All waste water shall be retained on
the car under freezing conditions.
* End of Chapter 15 *
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