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.
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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.
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 . . .
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.
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.
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.
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...