Hoffman Purge/Pressurization Manual for Models PLCF1YZ PLCB1YZ

Hoffman Purge/Pressurization Manual for Models PLCF1YZ PLCB1YZ
Hoffman Purge/Pressurization
Manual for Models
PLCF1YZ
PLCB1YZ
This manual covers Type Y/Z - Purge with Leakage Compensation
CONTENTS:
1. Specification Sheet – LC Y/Z – Purge/Pressurization Units
2. Application Suitability
3. Installation, Operation and Maintenance for LC Unit
Section 0. Description and Principle of Operation
Section 1. Installation of the Unit
Section 2. Operation of the Unit
Section 3. Maintenance of the Unit
Section 4. Fault Finding - LC Unit
4. Drawings
5. Certificates
1. Specification Sheet – Hoffman Purge/Pressurization Units
Model No. (Example):
P LC B 1 YZ
(Note: Not all codes are applicable)
Purge Unit Type
P=
Purge/Pressurization Unit
Approvals / Certifications
Y=
LC =
Leakage Compensation
0518
II 2 (2) G D
Ex [py] II T6 Gb
Ex [p] IIIC T85ºC Db
Tamb -20ºC +55ºC
Mounting Style
B=
F=
Back Plate (Top/Side Mount) 316L
Stainless Steel (NROB finish)
Flush Mount (Side/Front Mount) 316L
Stainless Steel (NROB finish)
Size
1=
Z=
Europe
EN 60079-0, EN 60079-2,
EN 61241-0, EN 61241-4
Sira 14ATEX1045X
Purging Method
Purge flow rate 8 scfm, 225 Nl / min
0518
II 3 (2) G D
Ex [pz Gc] IIC T6 Gb
Ex [p Dc] IIIC T85ºC
Tamb -20ºC +55ºC
IEC
IEC 60079-0, IEC 60079-2,
IEC 61241-4
IECEx SIR14.0019X
Ex [py] II T6 Gb
Ex [p] IIIC T85ºC Db
Tamb -20ºC +55ºC
Ex [pz Gc] IIC T6 Gb
Ex [p Dc] IIIC T85ºC
Tamb -20ºC +55ºC
USA / Canada NFPA 496
UL E466718
Class I Div 1
Groups A, B, C & D
Class I Div 2
Groups A, B, C & D
For limitations and conditions of use refer to the applicable certificate at the back of this manual.
Supply Pressure:
60 psi / 0.4MPa / 4 barg must be regulated at inlet.
Maximum supply pressure 115 psi / 0.8MPa / 8 barg. Compressed Air / Nitrogen
Flow & Pressure Sensors
"Low Pressure Sensor":
"Flow Sensor":
0.2 "WC / 50 Pa (0.5 mbarg)
1.38 "WC / 350 Pa (3.5 mbarg)
Leakage Compensation:
Variable up to 2 scfm (60 Nl/min) to compensate for Enclosure Leakage
Relief Valve
Opening Pressure:
Material:
4” WC / 1 kPa (10 mbarg)
316L Stainless Steel, Spark Arrestor: Stainless Steel mesh, Neoprene Gasket
Action on “Loss of Pressure”:
ALARM ONLY
Alarm Switch (Signals)
Zone 2 /Division 2
“Alarm”: Dry, VFC, SPSTN/O Contact
NI – Ex nA Non-incendive Circuits
Vmax <254 V ac rms
Imax < 1 A
Zone 1 or 2 / Division 1 or 2
IS – Ex i circuits
Umax = 30 Vdc
Imax 0.7 A
Hermetically Sealed Switch
Ex m IIC T4 Gc
Vmax =254 Vac rms
Imax 0.7 A
2. Application Suitability
Hoffman Purge/Pressurization Units are certified for use in Hazardous Areas, where the
Hazardous Area is non-mining (i.e. above ground) and the hazard is caused by flammable
gasses, vapors or dust.
Z-Purge Units may be used in IECEx, ATEX Zone 2(22) - Category 3 and NEC 500 Class I, Div
2.
Y-Purge Units may be used in IECEx, ATEX Zone 1(21) - Category 2 and NEC 500 Class I, Div
1.
Hoffman Purge/Pressurization Units may be used for hazards of any gas group. However,
apparatus associated with the Hoffman Purge/Pressurization Unit, such as Non-Incendive,
Intrinsically Safe signaling circuits and flameproof enclosures containing switching devices may
be limited in their gas group. The certification documentation supplied with any such devices
must be checked to ensure their suitability.
This unit is designed for use primarily with compressed air. Where other inert compressed
gasses are used (Nitrogen, for example) the User must take suitable precautions so that the
buildup of the inert gas does not present a hazard to health. Consult the Control of Substances
Hazardous to Health (COSHH) data sheet for the gas used. Where a risk of asphyxiation exists,
a warning label must be fitted to the Pressurized Enclosure.
The following materials are used in the construction of Hoffman Purge/Pressurization Units. If
substances that will adversely affect any of these materials are present in the surrounding
environment, please consult Hoffman for further guidance.
Materials of construction:
Stainless Steel
Aluminum
Mild (carbon) Steel
Nylon
Brass
Polyurethane
Acrylic
Silicone Rubber
Neoprene
3. Installation, Operation and Maintenance for LC Units
This Hoffman Purge/Pressurization Unit is designed for use under normal industrial conditions
of ambient temperature, humidity and vibration. Please consult Hoffman before installing this
equipment in conditions that may cause stresses beyond normal industrial conditions.
The Hoffman Purge/Pressurization Unit shall be installed and operated in accordance with
relevant standards, such as IEC / EN 60079-14, NEC 500, NFPA 496 and any local codes of
practice that are in force.
For IEC / ATEX applications, references to the NFPA 496 within this instruction manual, should
be replaced by the equivalent clause in IEC / EN 60079-2.
For IEC / ATEX applications, the "Example calculations:" in section 1.1.4 within this instruction
manual, should read:
If the PE external dimensions indicate a volume of 0.5 m3 (17.7 Ft3) then,
0.5 m3 (or 17.7 ft3) enclosure volume x 5 volume changes = 12 minutes purge time
0.225 m3/min (or 8 scfm) purge flow rate
Installation, Operation and Maintenance Manual for Hoffman Purge/Pressurization Unit
Leakage Compensation (Model LC) conforming to NFPA 496
IMPORTANT NOTE It is essential, to ensure conformity with the standard,
that the User of the unit observes the following instructions.
Please refer to the latest standard for detailed requirements and definitions.
Contents:
Section 0 Description and Principle of Operation
Section 1 Installation of the Unit
Section 2 Operation of the Unit
Section 3 Maintenance of the Unit
Section 4 Fault Finding
Section 5 Annex (if applicable)
Section 0 Description and Principle of Operation
All Hoffman Purge/Pressurization Unit pressurization units
provide:
prevent sparks being ejected from the PE through the RLV
aperture.
a) a method of pressurizing a Pressurized Enclosure (PE)
while at the same time compensating for any leakage,
together with
0.1 “Leakage Compensation” Units, Model LC
A Leakage Compensation (LC) Unit is intended to have
minimal flow after the initial purge time. The PE is built as
leak tight as possible and the LC unit merely tops up for any
enclosure leakage. The unit provides an initial high flow of
purging air that leaves the PE through the Relief Valve. After
the initial purging has been completed the Control Unit
changes over to Leakage Compensation mode and the
Relief Valve closes. The only flow thereafter is the flow
through the “Leakage Compensation Valve” (LCV) which is
adjusted so that the flow is enough to compensate for any
leakage from the PE. The Purging Flow rate is monitored by
a separate “Purge Flow Sensor” located in the CU, which
detects the differential pressure across the purge flow orifice
located directly before the RLV. The Purge Flow Sensor is
set to operate when the desired differential pressure is
exceeded. The output from the Flow Sensor is indicated on
the CU.
b) a method of purging the enclosure, before power is turned
on, to remove any flammable gas that may have entered the
enclosure while it was not pressurized.
Type Leakage Compensation (LC) unit is comprised of the
following two major parts:
- A Control Unit (CU) containing as a minimum, for “Y/Z”
Pressurization, a Leakage Compensation Valve (LCV),
Minimum Pressure and Purge Flow sensing devices, and a
“Pressurized”/”Alarm” indicator. The CU supplies a
‘Pressurized’ signal showing whether the PE pressure is
satisfactory or not.
- A Relief Valve (RLV), fitted to the PE, to provide a means
of limiting the maximum pressure experienced by the PE
during operation. All RLVs incorporate a Spark Arrestor to
Section 1 Installation of the Unit
The installation of the Hoffman Purge/Pressurization
Unit, the protective gas supply, any alarm device should
be in accordance with the requirements of NFPA 496.
The electrical installation associated with the
Hoffman Purge/Pressurization Unit shall conform to the
local codes and the relevant clauses of NFPA 496.
1.1 Installation of the Hoffman LC Unit
1.1.1 The Hoffman Purge/Pressurization Unit should be
installed either directly on or as close as possible to the
Pressurized Enclosure (PE). It should be installed so that the
unit indicators may be readily observed.
1.1.2 All parts of any unit carry a common serial number. If
installing more than one unit, ensure that this commonality is
maintained on each installation.
1.1.3 Any tubing, conduit and fittings used to connect to the
PE should be metallic, or, if non-metallic, conform to the
local codes for flammability ratings. No valve may be fitted in
any tube connecting the Hoffman Purge/Pressurization Unit
to the PE.
1.1.4 The User or manufacturer of the PE shall determine
the volume of the PE, the necessary purging volume, and
the time to be allowed for purging, using the chosen Hoffman
Purge/Pressurization Unit purging flow rate. It is the User's
responsibility to verify or enter this data on the PE and/or
unit nameplate. Ask Hoffman if in doubt.
Example calculations:
a) If the PE external dimensions give a volume of 20 cubic
feet, and it is NOT a motor, multiply the volume by four to get
the Purging Volume i.e. 80 cubic feet. Divide the Purging
Volume by the purge rate e.g. 32 cubic feet per minute, and
round up to the next even minute above, i.e. Purging time
would be 4 minutes.
b) If the PE is a motor, multiply the internal free volume by
ten to get the Purging Volume. For the example above,
Purging time would be 8 minutes.
1.1.5 If the PE contains an internal source of release of
flammable gas or vapor, the procedures for assessment of
the release as given in NFPA 496 shall be observed. The
User must verify that the specification of the Hoffman
Purge/Pressurization Unit e.g. pressures, type of protective
gas are correct for the specific application.
1.1.6 More than one PE can be protected by a single unit. If
PEs are connected and purged in “series” e.g. “Daisy
Chained”, the Outlet Orifice must be fitted on the last
enclosure with the Purge Inlet to the first enclosure. The
bore and length of the tube or conduit used to interconnect
the enclosures is critical and will determine the maximum
pressure experienced by the first enclosure in the series.
Advice on sizing can be obtained from Hoffman. The test
pressure for all the enclosures should be 3 times the
pressure inside the first enclosure when purging is taking
place. If PE’s are to be connected in parallel each enclosure
must have its own outlet Relief Valve, Purge Flow Sensor
and Pressure Sensor.
1.2 Quality and Installation of the Pressurizing Air or
Inert Gas Supply
1.2.1 The source of the compressed air must be in a nonclassified area. Inert gas may be used as an alternative to
compressed air.
1.2.2 Unless a supply shut-off valve has been specially fitted
within the unit, a valve with the same, or larger, thread size
as the Control Unit inlet fitting shall be fitted externally. In
addition, for "Y/Z" Pressurization units, a suitable indicator
shall be provided.
1.2.3 The tubing and fittings used must conform to 1.1.3
above.
1.3 Provision and Installation of Alarm Devices
Hoffman Purge/Pressurization Units have a Minimum
Pressure Sensor set to a pressure of at least 0.1” WC (0.25
mbar). When the PE pressure is above this set point the
Sensor produces a positive "Pressurized" signal. This is
displayed on a Red/Green indicator. This signal is used to
operate an electrical contact for a remote “Alarm”, suitable
for an Intrinsically Safe circuits, in accordance with Hoffman
drawing 89107938 (or for a Non-Incendive)
When the enclosure pressure falls below the set point of the
Sensor the "Pressurized" signal is removed, i.e. the absence
of the signal indicates an “Alarm” ("Pressure Failure")
condition. The User must make use of this external alarm
facility in accordance with NFPA 496 requirements, if the unit
“Alarm” indicator is not located in a place where it can be
readily observed.
The Alarm switch will reset and its contacts can be used to
operate a remote electrical alarm.
Hoffman application tip: Exception: For a “Z Purge”
unit fitted in a Division 2 area, a non-classified switch
inside the PE can be used to operate a remote Alarm
provided its electrical supply comes from within the PE
(i.e. NOT PROVIDING DRY CONTACTS). When the PE
power is switched off there is no need for an alarm.
1.4 Power Supplies and their Isolation
1.4.1 All power entering the PE shall be provided with a
means of isolation. This requirement also applies to any
external power sources that are connected to "dry contacts"
or "volt-free contacts" within the PE. Exception: Power to
Intrinsically Safe, or other apparatus, which is already
suitable for the location, need not be isolated by the Hoffman
Purge/Pressurization Unit. When utilizing "Y/Z"
Pressurization the power may be controlled manually by the
User by the use of local isolating switch.
1.4.3 The Power (cut-off) Switch must be approved for the
location or located in a non-classified area.
1.4.4 No valves are permitted between the Power Switch
and the Hoffman Purge/Pressurization unit.
1.5 Marking
1.5.1 The Hoffman Purge/Pressurization Unit carries a
nameplate and a specification sheet, which give specific
data such as serial and models numbers, Pressure Sensor
settings, flow rates and purge time.
1.5.2 Other marking, for the PE, required by the standard
includes:
“WARNING - PRESSURIZED ENCLOSURE
This enclosure shall not be opened unless the
area is known to be free of flammable materials
or unless all devices within have been deenergized" "Power shall not be restored after the
enclosure has been opened until the enclosure
has been purged for ____ minutes at a flow rate
of _____."
Hoffman note: It is understood that NFPA 496 requires to deenergize of all devices that are not suitable for the hazard,
e.g. devices that are not Explosionproof or Intrinsically Safe.
For example, an explosionproof anti-condensation heater
would not have to be de-energized.
1.5.3 If Inert Gas is used as the Protective Gas and a risk of
asphyxiation exists, a suitable warning plate should be fitted
to the PE.
Section 2 Operation of the Unit
2.1 Initial Commissioning
2.2.1 Open the supply shutoff valve.
2.1.1 Check that the unit has been installed in accordance
with Section 1 of this manual.
2.2.2 Adjust the Leakage Compensation Valve (LCV) so that
the enclosure pressure rises to the point where the
“Pressurized” indicator turns green.
2.1.2 Disconnect the supply pipe from the inlet to the Control
Unit and blow clean air through for at least 5 seconds per
foot of length (15 sec / meter) to remove any debris, oil and
condensation.
2.1.3 Connect a temporary pressure gauge or liquid
manometer to the PE or Control Unit “Pressure Test Point”,
[on the LP Sensor, by the removal of the Red plug - 5/32”
(4mm) OD nylon tube].
2.2 Commissioning Leakage Compensation (LC) “Y/Z”
Units.
On LC “Y/Z” Purge units, proceed as follows:
2.2.3 Continue to raise the PE pressure until the Relief Valve
(RLV) opens. Check that the RLV opens at or below the
figure specified in the documentation. Repeat the test
several times.
2.2.4 Lower the PE pressure until the “Pressurized” indicator
turns Red. Check that the indicator turns Red at or above the
pressure specified in the documentation. Check the external
alarm contacts.
2.2.5 Open the LCV again and set the PE pressure to a level
around 50% of the RLV operating pressures. This “working”
pressure is not critical. The “Pressurized” indicator should be
Green.
2.2.6 Turn the Purge Control Valve “On”. This will start the
High Purge Flow and the “Purging” indicator should turn
Yellow. If the “Purging” indicator remains Black the flow
through the outlet valve is below the minimum for which the
Flow Sensor has been calibrated. Check the air supply
pressure at the inlet to the Control Unit while purging is
taking place. It must be above the minimum specified. If the
supply pressure is correct and the “Purging” indicator does
not turn Yellow, there is too much leakage from the
Pressurized Enclosure.
“Purging” does not start until the indicator turns Yellow
2.2.7 On LC “Z” Purge units the purge timing function is
performed by the User. When the “Purging” indicator turns
Yellow the Purge Flow is above the minimum required and
the purge time can start. The User must ensure that the time
delay between the indicator turning Yellow and the
application of power to the PE is not less than the minimum
time required to purge the PE as shown on the PE or
Purge/Pressurization Unit nameplate.
Never turn on the power without purging first unless
you have proved that the interior of the PE is gas free
and checked that the “Pressurized” indicator is green!
2.2.8 After the purge time is completed the Purging Valve
should be turned “Off”. The High Purge Flow will cease and
the air flow into the enclosure will then be controlled once
again by the Leakage Compensation Valve (LCV), it should
now be re-adjusted if necessary. The RLV should be closed
and the enclosure pressure around 50% of the RLV opening
pressure. If this is not so there are three possible situations:
a) Air continues to come out through the Spark Arrestor,
after High Purge has been turned “Off”, in considerable
quantity. The LCV is too far open and the air flow is holding
the RLV open continuously. Close the LCV slowly observing
the manometer or gauge (see item 2.1.3 above). The PE
pressure will start to fall as the flow decreases but eventually
the RLV will close and the pressure rise again. At this point
the Relief Valve will start to open intermittently as the PE
pressure rises to the point where it exceeds the RLV
opening pressure. When the RLV opens the pressure will fall
quickly to the point where the RLV recloses and the
enclosure pressure starts to rise again. This is entirely
normal for this type of RLV. Proceed now to b) below:
b) If the Relief Valve is opening intermittently the LCV is
slightly too far open. Observe the manometer or gauge.
When the RLV opens the enclosure pressure falls quickly to
the point where the RLV re-closes and the enclosure
pressure starts to rise again. This is entirely normal for this
type of RLV and shows that it is working correctly.
Continue to close the LCV until the cycling stops and the
enclosure pressure starts to fall. Carefully adjust the LCV
until the PE pressure is approximately 50% of the RLV
opening pressure and stable. This pressure may be around
2”WC (5 mbar) and will be the “normal working pressure”.
c) If, at the end of purging, the PE pressure falls below the
Minimum Pressure Sensor setting the LCV is not open far
enough. The LCV should be opened until the PE pressure is
around the normal working pressure.
2.2.10 Type “Y/Z” purge units do not control the enclosure
power. It is the responsibility of the User to switch off the
power whenever the enclosure pressure falls below the
minimum permitted i.e. when the “Pressurized” indicator
turns Red.
2.4 Normal Operation
2.4.1 Turn the air supply valve On or Off to start or stop the
unit,
2.4.2 The User must close the Power Switch only after the
enclosure has been pressurized and purged sufficiently to
ensure that the interior of the enclosure is gas free. It is the
User’s responsibility to shut off the power, as soon as
possible after a pressure failure.
Section 3 Maintenance of the Unit
The maintenance recommended for the unit consists of the
following, supplemented by any additional local requirements
imposed by the authority having jurisdiction.
- Check the condition of the air supply filter element. Clean
or replace it as necessary.
3.1 Initial Maintenance
3.2 Routine Maintenance
Hoffman recommends that the commissioning test be
repeated at least every six months. They include checking
the opening pressure of the Relief Valve, setting of the
Minimum Pressure Sensor, and the "Normal Working
Pressure" of the enclosure. In addition, the following checks
are also recommended at that time:
At least every two years, the following additional checks are
recommended:
- Apparatus is suitable for the Hazardous Location
- There are no unauthorized modifications
- The source of air is uncontaminated
- The interlocks and alarms function correctly
- Approval labels are legible and undamaged
- Adequate spares are carried
- The action on pressure failure is correct
- Check the RLV and any other Spark Arrestors. Remove
any debris or corrosion, or replace the Spark Arrestor with a
spare.
Section 4 Fault Finding – LC Units
4.1 General
If the unit does not behave in the manner described above
there is a fault. Some of the more likely faults are dealt with
below. If a cure cannot be effected by following the
procedure shown below please call Hoffman or your supplier
for further assistance. The unit has been designed for ease
of fault finding and many of the components fitted are plug-in
or sub-base mounted. Check components by substitution
only after establishing that such action is necessary. If the
unit is less than 12 months old, parts under warranty should
be returned to Hoffman for investigation, with a full report of
the fault and the unit Serial number. NOTE: As with any
pneumatic unit the greatest enemies are water, oil and
debris in the air supply. For this reason a dust and water
filter should always be fitted. But debris can enter from other
sources and it is vital therefore that the procedure described
in Section 2 is carried out before using the unit for the first
time, or following any disconnection of the pipework. Failure
to perform this work may cause damage, which will not be
covered under warranty.
Fault Finding NOTE: Before making the following checks
verify that the main supply pressure is between 60 and 115
psi (4-8 bar) at the Control Unit.
4.2 Minimum Pressure Alarm is ON Continuously
(“Pressurized” Indicator is Red)
Possible cause 1: The Pressurized Enclosure (PE)
pressure is too low. Try increasing the setting of the Leakage
Compensation Valve (LCV) to raise the pressure in the PE.
This is accomplished by turning the LCV in a
counterclockwise direction.
Possible cause 2: Enclosure fault?
- Is the ACTUAL PE pressure below the setting of the
Minimum Pressure Sensor? Check it with a manometer or
gauge.
- Is there debris stuck on the face of the Relief Valve (RLV)
disk, perhaps held there because of the magnetic material?
- Has the PE door been closed and all conduit/cable glands
sealed?
- Is the PE leaking too much?
- Has the pressure sensing tube been damaged?
Possible cause 3: unit fault?
If checks above reveal that the PE is correct, the fault
probably lies in the Control Unit. The basic operation of the
Minimum Pressure Sensor can be checked by unscrewing
the 2.4” (60mm) diameter diaphragm and, by using a finger,
block the threaded hole in the top of the valve module. The
valve should operate and the indicator should turn Green. If
this works correctly and the enclosure pressure is above the
setting of the Minimum Pressure Sensor it is likely that the
Pressure Sensor diaphragm needs re-calibrating or
replacing. (See 4.6)
4.3 Relief Valve Opens (Continuously or Intermittently)
Possible cause 1: The PE pressure is too high.
The Leakage Compensation Valve (LCV) is too far open.
Adjust the LCV as described in Section 2 above.
Possible cause 2: Debris on the RLV disk allowing air to
leak from the valve. Remove the RLV cover and clean the
valve disk. The disk and spring may be removed from the
RLV without affecting the calibration.
4.4 “Purging” Indicator Will Not Turn Yellow During
Purging
Possible cause 1: Insufficient purging Flow due to
inadequate air supply pressure. Check the air supply
pressure at the inlet to the CU when flow is taking place.
Excessive pressure drop in the supply pipe is a very
common cause of this problem. The supply pipe must be at
least as big as the CU inlet fitting, i.e. at least ½” NB (12
mm).
Possible cause 2: Excessive Pressurized Enclosure (PE)
leakage. Check around the PE when flow is taking place.
Any significant leakage must be cured. Has a Leakage Test
been done? The total leakage should not exceed 10% of the
Purge Flow Sensor setting. Check for leakage down the
conduit through unsealed stopping boxes.
Possible cause 3: PE not strong enough. Repeat the PE
pressure test. It is recommended that the PE is tested to
three times the Relief Valve opening pressure e.g. 12”WC
(30 mbar) for units with default settings.
Possible cause 4: The tubing from the RLV Flow Sensing
point to the Purge Flow Sensor is not air-tight e.g. fitting nuts
not tightened or tube damaged. Check and repair as
necessary.
Possible cause 5: The Purge Flow Sensor is not operating
correctly or out of calibration. The basic operation of the
Purge Flow Sensor can be checked by unscrewing the 2.4”
(60 mm) diameter diaphragm and by using a finger, block
the threaded hole in the top of the valve module. The valve
should operate and the indicator turn Yellow. If this works
correctly and the flow through the Relief Valve is above the
minimum required WITH THE RELIEF VALVE COVER
FIRMLY SECURED IN PLACE the Sensor diaphragm needs
re-calibrating or replacing.
4.6 Pressure Sensor Calibration
If it is decided that the Minimum Pressure Sensor or Purge
Flow Sensor needs re-calibrating it can either be returned to
Hoffman for this service or it can be done by the User as
follows:
Disconnect the pressure sensing pipe from the top of the
diaphragm. (It is a “push-in” quick release fitting; firmly push
inwards the collar surrounding the pipe where it enters the
fitting, and then pull the pipe outwards while maintaining the
pressure on the collar). Unscrew the 2.4” (60 mm) diameter
diaphragm housing from the top of the Sensor. Invert it and
note the brass adjusting screw in the center. Turning the
screw inwards (clockwise) will lower the setting. It is likely
that the screw will be very stiff due to the locking sealant. If
the screw cannot be moved the application of gentle heat in
the area of the brass screw can often help. DO NOT
OVERHEAT!
4.7 Filter Cleaning
If the filter element needs cleaning the transparent bowl can
be unscrewed and removed. The filter element also
unscrews and can then be cleaned in soapy water. Do not
use solvents on any part of the filter assembly.
It is sometime easier, if the bowl is very tight, to remove the
filter by undoing the fitting that holds the filter into the Control
Unit.
Quick Installation Guide – PLCB1YZ
1.
With aid of supplied mounting template, cut
mounting holes into enclosure. Ensure that
Control Unit and Relief Valve are diagonally
opposed.
2.
Fix Control Unit to enclosure
3.
Fix Relief Valve to enclosure
4.
Connect Control Unit (Purge Flow Switch) and
Relief Valve with 6mm OD, Nylon tubing
5.
Connect output (dry contact alarm) as required
6.
Connect isolated air supply to Control Unit
7.
Ensure enclosure door is closed, fully latched and
free of leaks
8.
Turn on 60 PSIG (4 bar) air supply (115 PSIG/8
bar max)
9.
Slowly increase Leakage Compensation Valve
until Alarm Indicator turns from RED to GREEN
10. Turn Purge Control Valve ON and ensure Purge
Indicator turns from BLACK to YELLOW
11. After Purge time has been completed turn Purge
Control Valve OFF
12. Power can now be applied to the enclosure
13. Refer to manual for assistance
Quick Installation Guide – PLCF1YZ
1.
With aid of supplied mounting template, cut
mounting holes into enclosure. Ensure that
Control Unit and Relief Valve are diagonally
opposed.
2.
Fix Control Unit to enclosure
3.
Fix Relief Valve to enclosure
4.
Connect Control Unit (Flow Sensor) and Relief
Valve with 6mm OD, Nylon tubing
5.
Connect output (dry contact alarm) as required
6.
Connect isolated air supply to Control Unit
7.
Ensure enclosure door is closed, fully latched and
free of leaks
8.
Turn on 60 PSIG (4 bar) air supply (115 PSIG/8
bar max)
9.
Slowly increase Leakage Compensation Valve
until Alarm Indicator turns from RED to GREEN
10. Turn Purge Control Valve ON and ensure Purge
Indicator turns from BLACK to YELLOW
11. After Purge time has been completed turn Purge
Control Valve OFF
12. Power can now be applied to the enclosure
13. Refer to manual for assistance
Relief Valve Drawing
Relief Valve Cutout
Schematic for both PLCB1YZ and PLCF1YZ
Relief Valve Location
Alarm Switch (Signals)
Zone 2 /Division 2
“Alarm”: Dry, VFC, SPSTN/O Contact
NI – Ex nA Non-incendive Circuits
Vmax <254 V ac rms
Imax < 1 A
Hermetically Sealed Switch
Ex m IIC T4 Gc
Vmax =254 Vac rms
Imax 0.7 A
Zone 1 or 2 / Division 1 or 2
IS – Ex i circuits
Umax = 30 Vdc
Imax 0.7 A
Notes for Fig 1 Single channel interface circuit
1 Electrical equipment connected to associated apparatus should not use or generate more than 250
volts
2 Installation shall be in accordance with the manufacturer’s instructions and Article 504 of the
NEC(ANSI/NFPA 70)
3 For guidance on Installation see ANSI/ISA RP12.6, (Installation of IS Instrument Systems in Class I
Hazardous Locations)
4 Voc or Vt of associated apparatus is less than Vmax Isc or It of associated apparatus is less than Imax
Ci plus capacitance of interconnecting cabling is less than Ca of the associated apparatus
Li plus inductance of interconnecting cabling is less than La of the associated apparatus
5 "Simple Apparatus" is a device that will not generate or store more than 1.2V, 0.1A, 25mW or 20uJ
6 In Div 2 the circuit connected to the switch may be alternatively be Non-incendive in accordance with
NFPA70 Art 500-4(f)(1)
Hoffman Enclosures, Inc
2100 Hoffman Way
Anoka, Minnesota 55303-1745 USA
Phone: 763 422-2211
www.hoffmanonline.com
P/N 89108869
Dwg 89109561 A
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