Ashcroft P-N7 pressure switches - Manual

Installation and Maintenance Instructions for
ASHCROFT ® Type B700XD2 & D700XD2 & P-Series
Snap Action Switches with Dual Seal Rating
Note: This sheet contains information necessary for proper and
safe operation and should be read by the installer or user. DO
NOT DESTROY.
Do not exceed electrical, pressure or temperature ratings on
Name plates – turn off power before removing electrical cover.
Install in accordance with National Electrical Code or other
Applicable specifications. Process fluid type and temperature
must be compatible with the wetted materials shown on the
nameplates.
The Ashcroft ® dual diaphragm pressure actuator is designed to
meet the requirements of ANSI/ISA-12.27.01-2003 for process
sealing between electrical systems and flammable or com-
bustible process fluids. The testing for the Dual Seal Rating was
done by CSA and is part of CSA File LR 55541
© 2009 Ashcroft Inc., 250 East Main Street, Stratford, CT 06614-5145, USA, Tel: 203-378-8281, Fax: 203-385-0499, www.ashcroft.com
All sales subject to standard terms and conditions of sale.
I&M009-10171-09/09
OPERATION
The basic Ashcroft pressure switch actuator consists of a sens-
ing piston of a specific area exposed to process pressure. The
pressure on this area creates a force, which is opposed by a
spring until the set point is reached, at which point the switch
actuates. Various area piston and springs are used to get the
different ranges we offer.
The dual diaphragm design consists of a primary or sensing
diaphragm as described above and a secondary or redundant
seal diaphragm. In the unlikely event that the primary
diaphragm ruptures, the secondary diaphragm prevents
process fluid from entering the switch enclosure. A vent is pro-
vided to annunciate a primary seal failure.
Caution: The vent must not be used or blocked; gas leakage
may not be visible.
For inches of water ranges the D700, PDA, PDD and PDS switches are used as pressure switches not differential switches. The H
connection is used as the process input and the L connection as the vent.
Test/Internal Pressure
Atmospheric Pressure
Test/Internal Pressure
Atmospheric Pressure
Vent
Process
Connection
Spring Lower
Housing
Upper
Housing
Primary
Diaphragm Plate
Primary
Diaphragm Seal
Fastener
Assembly
Secondary
Diaphragm
Vent
Primary
Diaphragm
Vent
B, V, & T Actuators S or P Actuators
The XD2 option for B700, PPA, PPD and PPS
switches in the ranges of 15 psi to 600 psi.