Temperature Regulator RT-921 Series Self-Actuated FEATURES

Temperature Regulator RT-921 Series Self-Actuated FEATURES
Sales Manual Section 160
PRODUCT SPECIFICATION RT-921
Self-Actuated
Temperature Regulator
RT-921 Series
FEATURES
1.
2.
3.
4.
5.
6.
7.
8.
Seamless Robertshaw bellows used for closer control
and extended life.
Setpoint adjustment wheel.
Chevron "Lifetime" stem packing made of Teflon*
or EPT rubber U-cup for water service.
Sturdy construction with bronze frame.
Variety of sensing bulb forms and materials.
(See inside).
Valves in range of sizes, actions, styles, materials, etc.
for many services. (See inside).
Capillary selection of materials and lengths.
(See inside).
RT-921-A1 non-indicating unit shown.
RT-921-B1 offers integral temperature indication.
*Registered trade name of DuPont Co.
GENERAL
Without need for external power, Robertshaw Self-Actuated
Temperature Regulators (SATR) offer final control of the
temperature of a liquid, an air space or flow, or gas flow for
domestic, equipment, process, space, etc. on heating or cooling
service.
The SATR sensing bulb is installed in the medium being
controlled while the SATR valve is located on the supply line of
the medium used as the heating (steam, hot water) or cooling
(water, ethylene glycol, brine) agent. The SATR regulates the
heating or cooling medium flow to maintain the desired
temperature at the sensing bulb location. Robertshaw SATRs
are usually cataloged to detail the two-way direct acting (close
on temperature rise) type valves for heating service. Two-way
reverse-acting (open on temperature rise) and three-way valves
are equally available for cooling service.
Robertshaw SATR series offers a selection of: Throttling
bands, Temperature Indication, Fail-safe, Manual Positioning in
addition to automatic control, Corrosive atmosphere resistant
type, Small overall size and instantaneous heat exchanger
service.
Most cataloged Robertshaw SATR specifications are
starting points from which many alternates to cataloged
capillary, sensing bulb, separable well and valve may be
FURNISHED TO MEET YOUR SPECIFIC application's
needs.
1
(RT-921-A1 Illustrated)
Small Overall Size
Wide Throttling Band
HOW TO ORDER
1. Quantity
2. Size
3. Series number
4. Setpoint and/or setpoint range
5. Capillary specs.
6. Sensing bulb specs.
7. Valve type, action, ends, etc.
8. Other features
9. Shipping and invoicing instructions
RT-921 SERIES
The RT-921 series offers both non-indicating and integral
temperature indication control of liquid, air or gas with
steam or water as the heating source. The design is very
compact while offering sensitive control where smaller
valve sizes are involved. The series offers many alternate
specifications to match application needs. It is frequently
used for temperature control on "Original Equipment"
applications.
For cataloging and pricing purposes, the RT-921-Al and RT-921-BI series are detailed with direct
acting valves for heating service, 8 ft. capillary (copper tube with brass armor), type 12B (threaded
bushing) copper sensing bulb, bronze frame and other non-listed parts of non-ferrous metals.
Alternate specifications are available.
Valve sizes, Inches
1/4
Valve Type, Direct acting (closes with
rising temperature at bulb)
End Connections
Valve trim (poppet & seats), material
Valve stem (highly finished), material
Stem packing (spring loaded chevrons)
Valve Body, material
Body rating, pounds
Pressure drop limit, psi (For higher pressures, consult our
representative)
Full open Cv
3/8
1/2
Single-seated
Unbalanced
A
A
A
1/2" screwed unions
SS
SS
SS
SS
SS
SS
Teflon
Teflon
Teflon
Bronze
Bronze
Bronze
225
225
225
3/4
1
Single-seated
Balanced
MA
MA
Screwed unions
SS
SS
SS
SS
Teflon
Teflon
Bronze
Bronze
250
250
125
115
60
250
250
1.0
1.6
2.1
9.8
12.8
The RT-921-Al and RT-921-B1 series are available with
any of the setpoint ranges listed below. The range should be
selected so that the setpoint falls within the upper third of
the range span.
Setpoint
Adj. Range
Matching Setpoint
Temperature
Indication
Setpoint
Adj. Range
10° to 55° F
35° to 80° F
55° to 105° F
70° to 120° F
80° to 130° F
110° to 165° F
120° to 175° F
-60° to 80° F
-10° to 110° F
-10° to 130° F
10° to 160° F
20° to 185° F
30° to 195° F
40° to 205° F
160° to 210° F
170° to 215° F
195° to 240° F
205° to 250° F
230° to 280° F
250° to 300° F
Matching Setpoint
Temperature
Indication
80° to 245° F
100° to 240° F
130° to 265° F
130° to 280° F
160° to 310° F
170° to 330° F
ALTERNATE SPECIFICATIONS:
Capillary:
Length ............................................1 ft. to 50 ft. or more.
Materials ..........Copper tube with brass armor (standard)
or 304 stainless steel tube with or w/o SS braid.
Sensing Bulbs:
Type 12B .............................................. Copper (standard)
Type 12BP........................................... 316 stainless steel
Type 12B or 12BP ......................... with "dead extension"
Type 54 ............... Copper, externally finned, plain (54A),
bushed (54J) or flanged (54K).
Type 6 .......................................... Plain for open vessels,
Copper with copper tube and brass armor (6A),
or 316 SS with 304 SS tube and no braid (6AP).
Separable Wells: (for sensing bulb protection or ease of
removal)
Material ................................................................316 SS.
Type GA or GA with lagging extension ............ mounting
thread one size larger than bulb size.
Type GB ............. mounting thread same size as bulb size.
Valves: .............Types A, FA, MA, MAS, WA as illustrated.
VALVE SIZING
Valve sizing is critical to control and life of regulator.
Use Robertshaw's "Flo-Rule" valve sizing slide rule and Cv
chart or contact our representative or factory.
NOTE 1- IMPORTANT - If valve seat leakage can cause
a problem or a hazard, the following should be taken into
account. Maximum leakage of new valves: single-seated
Types A, WA - 0.05% of full open valve capacity;
single-seated balanced Types MA, MAS - 0.01% of full
open valve capacity; double-seated Type FA - 0.5% of full
open valve capacity. This leakage will usually increase
somewhat as the valve seats wear in service.
NOTE 2 - IMPORTANT - Damage to or failure of the
thermal element with loss of charge will ordinarily result in
the regulator going to the "cold" position. The valve stem
moves "up" - thus a "direct-acting" valve will fully open, a
"reverse-acting" valve will close, and a three-way valve
will fully open the "bottom" port. The normal result in
event of loss of thermal charge is overheating.
2
Dimensions, Shipping Weights and Sensing Bulb Sizes
Valve Size,
Inches
Direct-acting
Valve, Type
Shipping Wt.
Lbs.
A
B
D
E
1/4
3/8
1/2
3/4
1
A
A
A
MA
MA
27
27
27
29
32
8-27/32
5-13/32
3-7/16
6-15/16
8-27/32
5-13/32
3-7/16
7-1/8
7-31/32 7-31/32 7-31/32
5-13/32 5-13/32 5-13/32
1-9/16 1-9/16 1-9/16
4-3/4
4-3/4
4-3/4
Cataloged bulb for temperature ranges starting above 160° F.
G
1
1
1
1
1
H
11
11
11
11
11
T*
1
11
11
1
11
**Cataloged bulb for temperature ranges starting below 160° F.
G
1
1
1
1
1
H
11
11
11
11
14
T•
1
1
1
1
1
* Standard pipe thread.
** Bulb sizes for ranges beginning below 160° F. are necessary to provide
"cross-ambient" charge. This assures operation with ambient
temperatures either above or below the control setting. Under some
conditions, smaller bulbs may be used with lower ranges. If the larger
bulb cannot be used, consult the factory or nearest representative.
SATR Valves for RT-921-A1, RT-921-B1 Series
(See Valve Spec Sheet for full details)
THREE WAY VALVE
TWO WAY VALVES
Style A
Single Seated
Unbalanced
Direct & Reverse Acting
Sizes 1/4" - 1"
Union Ends
Bronze w/SS trim
Style MA & MAS
Single Seated, Fully Balanced
Direct Acting only
SS Trim
MA Sizes 3/4" - 1"
Union Ends, Bronze Body
MAS Sizes 3/4″ - 1″
Threaded Ends, Steel Body
MAS Size 1″
Flanged, Steel Body
Style FA
Double Seated
Semi-balanced
Reverse Acting only
Sizes 3/4" - 1", Union Ends
Bronze body
Bronze or Monel trim
Size 2”, Flanged
Bronze or Cast Iron body
Bronze, SS or Monel trim
SENSING BULB TYPES
Type 12 - (with pressure fitting
with threaded bushing)
3
Style WA
Unbalanced
Sizes 1/2" - 1"
Union Ends
Bronze body
SS trim
Type 12 (Continued)
- (with threaded bushing and "Dead Extension")
Type 6 - For non-pressurized containers (plain)
Type 54 - Externally finned for Air or Gases (315°
F. Max.)
Bulb Material – Copper / Brass
Standard Capillary - Copper tube with brass armor.
Diameters Available – 1”, 1-1/4" (See note *)
54A - with brackets for open space.
54J - with pressure fitting (threaded bushing)**
*
**
***
Fin O.D. for 1" diameter bulb is 1-3/4"; 2-1/4" for 1-1/4"
diameter bulb. Lengths are: 14" for 1" diameter bulb; 16" or
24" for 1-1/4" diameter bulb.
2" NPT for 1" diameter bulb; 2-1/2" NPT for 1-1/4" diameter
bulb.
Flange for 1" diameter bulb is 4-3/8 O.D. with 3-3/4" B.C.; for
1-1/4" diameter bulb flange is 4-7/8" O.D. with 4-1/4" B.C.
54K - with pressure fitting (flanged)***
SEPARABLE WELLS - For use with Type 12 bulbs up to 30" long.
Type GA
Type GA with 2" Lagging Extension'
Type GB
Q-4033 (11/04)
4
Printed in U.S.A.
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