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C645A,B,D,E
C645A,B with Window
GENERAL
The C645 pressure switches are safety devices used in
positive-pressure or differential-pressure systems to sense
gas or air pressure changes.
Copyright © 1995 Honeywell Inc. • All Rights Reserved
FEATURES
• C645A,B models are for use on natural gas, LP gas,
or air.
• C645B1047 includes a scaleplate stop to meet
American Gas Association (AGA) requirements for
gas-fired boilers with inputs over 2-1/2 million Btuh.
• C645C,D models are for use on air only.
• C645E for use with distillate fuel oil.
C645C
• Spring-loaded diaphragm actuates snap-acting
Micro Switch.
• Switch can be wired to turn on alarm.
• C645A,C and D models break control circuit on
pressure fall.
• C645B models break control circuit on pressure rise.
• Lockout and manual reset optional in A and C models.
• Removable, zinc-plated cover protects scaleplate and
adjusting screw.
• Lockout models have external manual reset lever.
• Pipe tappings allow selection of positive pressure,
differential-pressure, or venting connections.
• Optional switch position indicator available.
• Models of C645A,B available with cover window for
setpoint visibility.
• Buna-N fiber-reinforced material for increased control
diaphragm strength.
• Two seal-off diaphragms for added reliability.
General ............................................................................... 1
Features .............................................................................. 1
Specifications ...................................................................... 2
Ordering Information ........................................................... 2
Installation ........................................................................... 4
Settings and Adjustments ................................................... 6
Operation and Checkout ..................................................... 7
Pressure Switches
C645A-E
PRODUCT DATA
Contents
60-2159-8
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Summary of Contents for Honeywell C645A-E
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Page 1: Table Of Contents
The C645 pressure switches are safety devices used in positive-pressure or differential-pressure systems to sense gas or air pressure changes. Copyright © 1995 Honeywell Inc. • All Rights Reserved Pressure Switches FEATURES • C645A,B models are for use on natural gas, LP gas, or air. -
Page 2: Specifications
If you have additional questions, need further information, or would like to comment on our products or services please write or phone: 1. Your local Honeywell Home and Building Control Sales Office (check white pages of your phone directory). 2. Honeywell Home and Building Control Customer Relations... - Page 3 IMPORTANT: FOR MODELS WITH LOCKOUT, DO NOT OBSTRUCT MANUAL RESET LEVER. Fig. 1. Dimensions of C645A,B,D, and E in in. (mm). C645A-E PRESSURE SWITCHES Canadian Standards Association listed: C645A-E, File no. LR1620-369, Guide no. 140-A-2; for use subject to same ambient temperature restrictions as Underwriters Laboratories Inc.
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Page 4: Installation
C645A-E PRESSURE SWITCHES MOUNTING BRACKET (OPTIONAL) 5/16 (7.9) 1/4-18 INCH 3/16 (4.8) DIA. 3-5/8 (92) (127) 1-13/16 (46) 9/32 (7.1) DIA. (2) (25.4) (19) 2-1/4 (57.1) IMPORTANT: FOR MODELS WITH LOCKOUT, DO NOT OBSTRUCT MANUAL RESET LEVER. INSTALLATION When Installing this Product . . . - Page 5 0.015 in. (0.38 mm) diameter (nominal) orifice in its 1/4 in. NPT main (high pressure) connection. (This orifice is required in a C645A Gas Pressure Switch to restrict gas leakage, but it is too small for oil applications.) The C645E1002 has a 0.125 in.
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Page 6: Settings And Adjustments
C645A-E PRESSURE SWITCHES SETTINGS AND ADJUSTMENTS Pressure Setpoint Adjustment Tables 2 through 4 give the pressure and switching for each setpoint. To adjust the pressure setting, turn the setpoint adjustment screw (Fig. 3 and 4) clockwise the pressure setting and counterclockwise the pressure setting. -
Page 7: Operation And Checkout
Micro Switch snap-acting switch to break a control circuit when pressure falls to scale setting minus differential. The switch can be wired to turn on an alarm at the same time. When the pressure rises to the scale setting, the control circuit requires manual resetting to reset and turn off alarm. - Page 8 C645A-E PRESSURE SWITCHES Home and Building Control Home and Building Control Honeywell Inc. Honeywell Limited-Honeywell Limitée 35 Dynamic Drive 1985 Douglas Drive North Golden Valley, Minnesota 55422 Scarborough, Ontario M1V 4Z9 60-2159—8 F.P. Rev. 5-95 60-2159—8 www.honeywell.com/bbc...