Honeywell Switch C437D User Manual

C437D,E,F,G,H,J,K and C637B Gas  
Pressure Switches  
PRODUCT DATA  
FEATURES  
C437 models have direct- and reverse-acting (spst)  
switching; C637B has single-pole, double-throw (spdt)  
switching.  
Pressure ranges: 1/2 to 5-1/2 in. of water (10 to 140 mm  
of water, or 0.1 to 1.4 kPa); 1 to 26 in. of water (50 to  
700 mm of water, or 0.5 to 7 kPa); 1/2 to 5 psi (300 to  
3500 mm of water, or 3 to 35 kPa); 1 to 10 psi (500 to  
7000 mm of water, or 5 to 70 kPa).  
Models intended for lockout applications must be  
manually reset before resuming operation.  
Trip-free mechanism on manual reset models ensures  
that the limit function of the switch cannot be defeated  
by jamming the reset lever.  
External manual reset button on side of lockout  
models.  
Enclosed setting impedes tampering and provides  
dust-resistant operation.  
Buna-N fiber-reinforced material for increased  
strength of control diaphragm.  
Two Buna-N fiber-reinforced seal-off diaphragms for  
added reliability.  
Clear glass cover allows observation of interior  
mechanism to aid setting and checkout.  
Mercury switch provides visual indication of switch  
position.  
Heavy die-cast case increases durability and  
resistance to corrosion.  
Main control diaphragm completely enclosed a leak-  
proof chamber can be vented to a safe area.  
Models with a pressure range of 1 to 26 in. of water  
(50 to 700 mm of water, or 0.5 to 7 kPa) have a  
restrictive orifice in the inlet pressure channel to  
compensate for momentary surges in gas pressure.  
Field-addable orifices of various sizes are available.  
Models available with rainproof, dustproof, sleet- and  
ice-resistant enclosure; meets NEMA 3R specification.  
GENERAL  
The C437 and C637 Gas Pressure Switches are pressure-  
actuated switching devices used in industrial gas system  
applications for safety shutoff, pressure control, and  
differential-pressure control.  
Contents  
General ...............................................................................  
Features ..............................................................................  
Specifications ......................................................................  
Ordering Information ...........................................................  
Recycling Notice .................................................................  
Installation ...........................................................................  
Setting and Checkout ..........................................................  
1
1
2
2
4
4
6
Copyright © 1995 Honeywell Inc.  
All Rights Reserved  
60-2320-9  
 
C437D,E,F,G,H,J,K AND C637B GAS PRESSURE SWITCHES  
Switch:  
Mercury switch (C437F,J and K have two spst switches in one mercury bulb).  
Differentials:  
Fixed, nominal; measured at pressure indicated:  
Pressure Rangea  
1/2 to 5-1/2 in.  
(10-140 mm, or  
0.1-1.4 kPa)  
1 to 26 in.b  
(50-700 mm, or  
0.5-7 kPa)  
1/2 to 5 psi  
(300-3500 mm, or  
3-35 kPa) differential  
measurement at  
midscale  
1 to 10 psi  
(500-7000 mm,  
or 5-70 kPa)  
differential  
Differential Measured  
at 1/2 in.  
differential  
measured at 15 in.  
measurement  
Model  
Numbers  
in.  
mm  
kPa  
in.  
mm  
kPa  
psi  
1/2  
1/4  
mm  
352  
176  
kPa  
3.45  
1.72  
psi  
1c  
1/2e 352e 3.45e Additivef  
mm  
kPa  
Typea  
C437D,J  
1-3/4 44.5 0.44  
703c 6.89c Subtractived  
C437E,F,H,K  
C637B  
0.25e 6.4e  
0.06e 1-1/4 31.8 0.31  
0.15  
3.8  
0.04  
C437G  
1-1/4 31.8 0.31  
1/4  
176  
1.72  
1/2  
352 3.45 Subtractive  
a in. = inches of water; mm = millimeters of water.  
b Restrictive orifice in inlet pressure channel to compensate for momentary surges in gas pressure.  
c Not available for C437J.  
d Subtractive models: switching action occurs on pressure rise to the setpoint.  
e Not available for C437K.  
f
Additive models: switching action occurs on pressure fall to the setpoint.  
Pressure Ranges (Scale Range):  
Specify one:  
MinimumTemperature:  
32°F (0°C).  
1/2 to 5-1/2 inches of water (10 to 140 mm of water, or  
0.1 to 1.4 kPa).  
1 to 26 inches of water (50 to 700 mm of water, or 0.5 to  
Approvals:  
Underwriters Laboratories Inc. Listed: File No. MP2168,  
Guide No. MFHX.  
7 kPa).  
1/2 to 5 lb per sq in. (300 to 3500 mm of water, or 3 to  
Canadian Standards Association Certified: File No. 1620,  
Guide No. 380-W-1.16.  
35 kPa).  
1 to 10 lb per sq in. (500 to 7000 mm of water, or 5 to  
70 kPa).  
Factory Mutual Approved: Report No. 13031-S5 and  
19291.  
Maximum Sustained Operating Pressure:  
Maximum Pressure  
Replacement Parts:  
106729 Cover Glass, 6 in. (152.4 mm) diameter.  
139870A Cover Glass, for rainproof enclosures.  
106747 Cover Retaining Ring, for models manufactured  
before 1973.  
Pressure Range  
1/2 to 5-1/2 in. of water  
1 to 26 in. of water  
1/2 to 5 psi  
psi  
3.0  
kPa  
20.7  
118733-21 Retaining Clip, for models manufactured since  
1975.  
5.0  
34.5  
Accessories:  
15.0  
30.0  
103.4  
206.8  
4074BWK Bag Assembly: Contains two 137755 Mounting  
Brackets and four self-tapping screws: for surface  
mounting (standard on C437G and H). Mounting  
brackets are shown by dashed lines in Fig. 1.  
Field-addable Orifices:  
1 to 10 psi  
Pipe Connections:  
Main or High Pressure: 1/2 in. NPT, female.  
Vent or Low Pressure: 1/8 in. NPT, female.  
Electrical Wiring: Hole tapped for 1/2 in. conduit.  
124674: 0.011 in. (0.28 mm) diameter.  
122160: 0.018 in. (0.46 mm) diameter.  
Maximum AmbientTemperature:  
125°F (52°C).  
3
60-2320—9  
 
C437D,E,F,G,H,J,K AND C637B GAS PRESSURE SWITCHES  
6-1/4 (158.8)  
5/16 (7.9) (4)  
1
6-1/2  
(165.1)  
5/8  
(15.9)  
(4)  
7-3/4  
(196.9)  
7-11/16  
DIA.  
(195.3)  
2
45°  
45°  
1/8  
(3.2)  
1
(25.4)  
1-5/16  
(33.3)  
7-3/8 (187.3)  
1/8–27 NPT  
1/2–14 NPT  
TAPPED FOR 1/2 IN.  
CONDUIT  
2 (50.8)  
3-7/16 (87.3)  
1
2
137755 MOUNTING BRACKET (2), IN 4074BWK BAG ASSEMBLY – STANDARD  
ON C437G AND H; OPTIONAL ON OTHER MODELS.  
M7192  
VENT TAPPING. REMOVE DUST-SEAL LABEL BEFORE MOUNTING.  
Fig. 1. Installation dimensions of the C437 and C637 gas pressure switches, in in. (mm).  
INSTALLATION  
RECYCLING NOTICE  
This control contains mercury in a sealed tube. Do not  
place control in the trash at the end of its useful life.  
When Installing this Product  
Read these instructions carefully. Failure to follow them  
could damage the product or cause a hazardous  
condition.  
If this control is replacing a control that contains  
mercury in a sealed tube, do not place your old  
control in the trash.  
Check the ratings given in the instructions and on the  
product to make sure the product is suitable for your  
application.  
Installer must be a trained, experienced, flame  
safeguard control technician.  
After installation is complete, check out product  
operation as provided in these instructions.  
Contact your local waste management authority for  
instructions regarding recycling and the proper  
disposal of this control, or of an old control containing  
mercury in a sealed tube.  
60-2320—9  
4
 
C437D,E,F,G,H,J,K AND C637B GAS PRESSURE SWITCHES  
Use nipple and T for pipe mounting or the mounting  
bracket for surface mounting. If a mounting bracket is  
used, install the bracket before making piping  
connections (standard on C437G and H). Mount the  
bracket horizontally with the four 10-24 flathead tapping  
screws provided.  
CAUTION  
Disconnect all power to the pressure switch before  
beginning installation to prevent electrical shock and  
equipment damage.  
Level the device carefully.  
IMPORTANT  
a. Level the device so that the point of leveling  
pendulum is aligned with the mark on the inside  
of the case.  
b. When pipe mounting, install the device at right  
angles to the pipe so that it can be leveled by  
additional tightening of the pipe fittings.  
c. The surface mounting bracket has elongated  
holes that allow limited leveling after the mounting  
screws are started.  
d. Accurate leveling is most essential at very low  
pressure settings.  
1. Remove the dust-seal label from the vent tapping  
before mounting.  
2. Accurately level the pressure switch for proper  
operation.  
3. The C637B pressure switch is a low differential  
device. Mount it in a vibration-free location to prevent  
chattering.  
4. Do not hand tighten the pressure switch by holding  
the case.  
Follow local codes or ordinances in all cases when different  
from these recommendations.  
e. If necessary, make arrangements to hold pipe-  
mounted units steady and level with bracing.  
Fig. 1 shows the mounting dimensions for the C437 and C637  
models, and for the accessory mounting bracket (standard on  
C437G and H). See Fig. 2 for the individual components.  
Location  
PENDULUM  
Mount the gas pressure switch downstream from the pressure  
regulator. Mount low gas pressure switches upstream of any  
shutoff valve. Mount high gas pressure switches just  
upstream from the burner. When pipe mounting, locate the  
device on the portion of the pipe that is most level because  
the mercury switch requires level orientation. See step 4 in  
the Mounting section.  
LEVEL  
LINE  
MERCURY SWITCH  
PRESSURE SETTING  
INDICATOR  
M7196A  
SCALEPLATE  
SETTING  
SCREW  
Fig. 3. Properly leveled C437/637.  
UNDER  
RETAINER  
IMPORTANT  
MANUAL  
RESET  
To avoid leaks and case damage, use a parallel jaw  
wrench on the hexagonal part of the case close to  
the pipe. Carefully make all connections and test for  
leakage. Do not tighten the pressure switch by  
holding the case.  
BUTTON  
(CC437D,  
E,J,K)  
TERMINAL  
STRIP  
RETAINER  
Complete the main piping.  
Connect the piping to the pressure switch. Select the  
application from the following, and proceed as  
instructed.  
LEVELING  
PENDULUM  
VENT  
TAPPING  
(ON SIDE  
1
NOT SHOWN)  
CONDUIT  
TAPPING  
a. Hazardous-gas applications: Install a 1/8 in. NPT  
pipe at the vent tapping on all hazardous-gas  
applications.  
MAIN PRESSURE TAPPING  
LENS GASKET  
(G,H ONLY)  
M7630  
1
REMOVE DUST-SEAL LABEL BEFORE MOUNTING  
WARNING  
Fig. 2. Principal parts of the gas pressure switch.  
The vent must be installed so that any gas leakage is  
vented into a safe place in event of a diaphragm  
failure.  
Mounting  
Remove the dust-seal label from the vent tapping.  
Remove the screws and retainers, and the cover glass.  
Mount the device on the pipe or nearby vertical surface.  
b. Differential-pressure applications:  
5
60-2320—9  
 
C437D,E,F,G,H,J,K AND C637B GAS PRESSURE SWITCHES  
(1) Connect the high-pressure side of the  
system to the 1/2 in. NPT main pressure  
tapping on the gas pressure switch.  
(2) Connect the low pressure side to the 1/8 in.  
NPT vent tapping.  
RISE  
MAKES ON  
PRESSURE  
FALL  
MAKES ON  
PRESSURE  
RISE  
WARNING  
TERMINAL  
STRIP  
No venting is possible in this case. Do not use this  
device for differential pressure control with the  
hazardous gases.  
W
B
1
1
R
R
C437F,J,K  
c. Negative-pressure applications: Connect the low  
pressure side to the 1/8 in. NPT vent tapping.  
1
BOTH ENDS OF THE SWITCH (W-R AND B-R) MUST BE USED  
AT THE SAME VOLTAGE IN THE SAME BRANCH CIRCUIT.  
M7193  
Fig. 5. Wiring diagram for C437F,J,K.  
WARNING  
This application is for use only with nonhazardous  
gases. Do not use this device for negative-pressure  
applications with hazardous gases.  
RISE  
Install other controls in the system. Connect wiring, and  
complete setting and checkout before replacing the  
cover glass and retainers. See Setting and Checkout  
section.  
MAKES R TO W  
ON PRESSURE  
RISE  
MAKES R TO B  
ON PRESSURE  
FALL  
Wiring  
TERMINAL  
STRIP  
W
B
CAUTION  
R
1. Disconnect all power to the pressure switch  
before connecting wiring to prevent electrical  
shock and equipment damage.  
C637B  
M7194  
Fig. 6. Wiring diagram for C637B.  
2. When using a C437F,J, or K, both ends of the  
switch (W-R and B-R) must be used at the same  
voltage in the same branch circuit.  
SETTING AND CHECKOUT  
All wiring must comply with local electrical codes, ordinances,  
and regulations. Do not exceed the switch ratings given in the  
Specifications section.  
Setting  
In the C437D,G and J models, the differential is subtractive.  
The upper operating point is determined by the setpoint, while  
the lower operating point is determined by the setpoint minus  
the differential. In the C437E,F,H,K and C637B models, the  
differential is additive. The lower operating point is determined  
by the setpoint, while the upper operating point is determined  
by the setpoint plus the differential. Operating points are  
shown in Fig. 7.  
Wiring diagrams for the different models are shown in Fig. 4,  
5 and 6. The switches make or break as indicated in the  
diagrams. Connect the wiring to the screw terminals on the  
terminal strip after removing the cover glass. Route the wires  
through the conduit tapping.  
C437D,G: BREAKS ON PRESSURE RISE  
C437E,H: BREAKS ON PRESSURE FALL  
Remove the retainer and adjust the setpoint for the desired  
operating pressure (cutout pressure on a C437D,E,G, or H  
spst model) by turning the setting screw (Fig. 2) clockwise  
to increase the setpoint and counterclockwise  
decrease it.  
to  
TERMINAL  
STRIP  
Trip-Free Manual Reset Feature  
(C437D,E,J and K only)  
M7195  
The C437D breaks and the C437J breaks R-B and makes  
R-W when the pressure rises to the setpoint. The C437E  
breaks, and the C437K breaks R-W and makes R-B when the  
pressure falls to the setpoint. None of these pressure  
switches will automatically return to their former positions.  
Fig. 4. Wiring diagram for C437D,E,G,H.  
60-2320—9  
6
 
C437D,E,F,G,H,J,K AND C637B GAS PRESSURE SWITCHES  
To reset one of these pressure switches, wait until the  
pressure falls to the setpoint minus the differential (C437D or  
J), or rises to the setpoint plus the differential (C437E or K).  
Then depress the manual reset button (Fig. 2) and release it.  
The pressure switch will not be reset until you release the  
manual reset button. This prevents the switch from becoming  
an automatic-reset device if the reset button is stuck, held in,  
or tied down.  
Turn the setting screw toward a high pressure setting  
(clockwise  
) to simulate a pressure decrease  
greater than the differential. The C437G should make  
contact and turn on the controlled equipment.  
Push the manual reset button (Fig. 2) on the C437D or  
J; the C437D should make, and the C437J should  
break R to W and make R to B.  
C437E,F,H,K or C637B  
(Additive Differential)  
Checkout  
Adjust the setpoint for normal operation and check to see that  
the gas pressure switch performs as intended. Use a  
manometer or accurate pressure gauge connected upstream  
from the switch to measure the actual pressure.  
Put the system into normal operation and gradually  
close the upstream gas shutoff valve to cause a  
pressure decrease.  
When the pressure gauge indicates that the pressure is  
approximately equal to the setpoint, the C437E or H  
should break contact and turn off the controlled  
equipment; the C437F,K or C637B should break R to W  
and make R to B.  
The most likely cause of inaccurate operation is off-level  
mounting. Refer to step 4 in the Mounting section and correct  
any installation that does not check out satisfactorily.  
The C437E or K should lock out.  
C437D,G or J (Subtractive Differential)  
Open the gas shutoff valve to increase the pressure  
again. When the pressure rises to the setpoint plus the  
differential, the C437H should make contact and turn on  
the controlled equipment; the C437F or C637B should  
break R to B and make R to W.  
Put the system into normal operation, and set the  
pressure switch at the normal setpoint (above the  
normal operating pressure).  
Turn the setting screw (Fig. 2) slowly toward a lower  
pressure setting (counterclockwise  
pressure increase.  
When the setpoint is approximately equal to the  
pressure indicated on the pressure gauge, the C437D  
or G should break contact and turn off the controlled  
equipment; the C437J should break R to B and make R  
to W.  
) to simulate a  
Push the manual reset button (Fig. 2) on the C437E or  
K; the C437E should make, and the C437K should  
break R to B and make R to W.  
Completing the Installation  
Remove the pressure gauge or manometer used for  
testing. Visually recheck the piping, wiring, and setting.  
Replace the cover glass and retainers.  
The C437D or J should lock out.  
SET POINT  
(SWITCH BREAKS,  
Return the system pressure to normal.  
Push the manual reset button (C437D,E,J or K only).  
C437D LOCKS OUT)  
C437D,G  
SUBTRACTIVE  
DIFFERENTIAL  
PRESSURE  
RISE  
Installing a Pressure Orifice (Fig. 8)  
1
SET POINT MINUS  
DIFFERENTIAL (SWITCH MAKES)  
To compensate for momentary surges in gas pressure, install  
a restrictive orifice in the inlet pressure channel of the  
pressure switch. (Refer to Accessories in the Specification  
section for the orifice sizes available.)  
SET POINT  
(BREAKS R-B MAKES R-W  
AND LOCKS OUT)  
C437J  
SUBTRACTIVE  
DIFFERENTIAL  
PRESSURE  
RISE  
Align pressure orifice into reset located inside of the main  
pressure tapping at the bottom. Press orifice into place using  
1/8 in. dowel rod.  
1
SET POINT MINUS  
DIFFERENTIAL (BREAKS R-W,  
MAKES R-B)  
SET POINT PLUS  
DIFFERENTIAL (SWITCH MAKES)  
PRESSURE  
FALL  
ADDITIVE  
2
DIFFERENTIAL  
MAIN PRESSURE  
TAPPING  
C437E,H  
SET POINT  
(SWITCH BREAKS,  
C437E LOCKS OUT)  
PRESSURE  
ORIFICE  
(SELECTED)  
SET POINT PLUS  
DIFFERENTIAL (BREAKS R-B  
MAKES R-W)  
PRESSURE  
FALL  
2
ADDITIVE  
C437F,K  
C637B  
DIFFERENTIAL  
SET POINT  
(BREAKS R-W, MAKES R-B,  
C437K LOCKS OUT)  
C437D AND J ARE MANUAL RESET MODELS; THEY CAN BE  
MANUALLY RESET WHEN THE PRESSURE FALLS TO THE SET  
POINT MINUS THE DIFFERENTIAL.  
1
2
M7191A  
1/8 IN. DOWEL ROD  
Fig. 8. Installing a pressure orifice to compensate for  
pressure surges.  
C437E AND K ARE MANUAL RESET MODELS; THEY CAN BE  
MANUALLY RESET WHEN THE PRESSURE RISES TO THE SET  
POINT PLUS THE DIFFERENTIAL.  
M7197  
Fig. 7. C437 and C637 operating points.  
7
60-2320—9  
 
Automation and Control Solutions  
Honeywell International Inc. Honeywell Limited—Honeywell Limitée  
1985 Douglas Drive North  
Golden Valley, MN 55422  
35 Dynamic Drive  
Scarborough, Ontario M1V 4Z9  
60-2320—9 L.Z. Rev. 9-95  
customer.honeywell.com  
 

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