Ashcroft A Series - N4 Pressure Switch User Manual

Page 2

Installation and Maintenance Instructions

for Ashcroft A-Series Miniature

Watertight Pressure Switches

© 2011 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&M009-10045-10/11 (250-2966) Rev. 07/13

GROUND

INSTALLATION
• To minimize the risk of injury, the switch enclosure must be se-

lected according to the area classification and installed ac-
cording to the required safety and electrical codes.

• Torque should always be applied to the Hex portion of the

body, never to any other part of the body for it may alter the
setpoint. It is recommended that Teflon tape or other sealant
be used on the threads prior to installing to prevent leaks in
the system.

• The ambient temperature limits for the switches are –40° to

100°C (varies with seal ordered).

• Switch should be protected from excessive shock and vibration.
• The cover of the APA switch should be closed at all times

when the switch is in operation.

CAUTIONS
• Always close the cover of the APA switch after making any

setpoint adjustments.

• Do not exceed current or voltage limits.
• The protection degree of the switch is only valid when the

switch is installed in accordance with all safety and electrical
codes and regulations.

CLEANING
• Never use aggressive solvents.
• Do not use high pressure water to clean the switch.

MAINTENANCE/TROUBLESHOOTING
• All Ashcroft switches require little or no maintenance.
• Be sure the cover on the APA switch is closed at all times.
• When the switch is exposed to process media that may harden

and/or build up in the pressure port, the switch should be re-
moved and cleaned as required.

• If the switch does not function, only trained and skilled person-

nel should check on the wiring, power supply and/or mounting.

• If the problem cannot be solved, please contact one of the

Ashcroft affiliates or distributors.

FACTORY SETPOINTS
The APS switches and APA switches with a setpoint called out in
the product code are set at the factory as follows:
• Increasing Setpoint (R) Rising Pressure or Decreasing Vac-

uum – Normally Open contact will close when the pressure is
raised from 0 psig to the setpoint. The resetpoint is then meas-
ured from the setpoint, reducing the pressure until the Nor-
mally Open contact opens.

• Decreasing Setpoint (D) Decreasing Pressure or Increasing

Vacuum – Normally closed contact will close when the pres-
sure is lowered from full range pressure to the setpoint. The
reset is then measured from the setpoint, increasing the pres-
sure until the Normally Closed contact opens.

Note: When ordered as a –15/15 psi range switch, depending

on setpoint, the Normally Open contact may be closed
as received.

Safety Manual and SIL Certificate, CRN available on
www.ashcroft.com

SPADE TERMINALS

DIN CONNECTOR

1 – COMMON
2 – NORMALLY CLOSED
3 – NORMALLY OPEN

4 – Ground

WIRE COLOR/FUNCTION

WIRE COLOR

SWITCH

FUNCTION

RED

SW1

WHITE

SW1

BLUE

SW1

WHITE/BLACK

SW2

RED/BLACK

SW2

BLUE/BLACK

SW2

GREEN

–

Ground