Ashcroft LD - Differential Pressure Switches - Manual

Installation and Maintenance Instructions
for ASHCROFT
® L-Series Snap Action
Switches for Differential Pressure Control
OPERATION
The ASHCROFT
® differential pressure control is a precision
device which features a snap action switch. Fixed deadband is
available with single or dual SPDT independently adjustable
switches with various electrical ratings. Adjustable deadband is
available with a SPDT switch with various electrical ratings.
Several wetted material constructions for compatibility with
pressure media may be obtained.
Series LD-S switches have a fixed deadband which will be
within the limits noted on the nameplate.
Series LD-D switches may be set to operate simultaneously or
up to 85 percent of the range apart. The deadband of each
switch will be within the limits noted on the nameplate.
Series LD-A switches may be set to operate with any dead-
band within the limits shown on the nameplate.
MOUNTING
The “L” Series ASHCROFT
® snap action differential pressure
switch has a NEMA-4X enclosure which is an epoxy coated
aluminum casting.
Two holes in the integral bracket are used to surface mount
the control. Location of these holes is shown on the general
dimension drawings. An optional pipe mounting bracket is also
available. Mount on a vibration free surface or pipe in any
orientation.
PRESSURE CONNECTIONS
For operation as a differential pressure control – connect the
high pressure to the side port marked “H” and the low pressure
to the side port marked “L.”
CONDUIT CONNECTIONS
One
3 ⁄
4
NPT hole fitted with a shipping plug, and two additional
knock outs are provided. The knockouts may be removed by
placing a screwdriver in the slot and rapping sharply with a
hammer. It is recommended that Teflon tape or other sealant be
used on conduit bushing or plug threads to ensure integrity of
the enclosure.
ELECTRICAL CONNECTION
Remove cover, held in place by two screws.
On all units except one with terminal blocks – wire directly to
the switch according to circuit requirements. Units with terminal
blocks – wire directly to terminal blocks as required. Terminals
are marked common (C), normally open (NO) and normally
closed (NC).
STANDARD RANGES
30, 60, 90, 200, 400 psid
2.06
(52)
1.21
(31)
0.38 (10)
3.94
(100)
3.26
(83)
0.91
(23)
6.02
(153)
6.09
(155)
3/4 NPT
4.12
(105)
0.25
(6)
2.50
(64)
Ø 2. 3 1
( 5 9 )
1 / 4 N P T
LOW
L H
FEMALE
PRESSURE
PORT
1/ 4NP T
HIGH
FEMALE
P R ESSURE
PORT
4.1 lbs.
© 2007 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&M009-10016-10/00 (250-2871) AMR 12/07
1
2
3
1
2
3
LEFT SWITCH
TERMINAL BLOCK
RIGHT SWITCH
TERMINAL BLOCK
SERVICE LEADS TO THESE TERMINALS
NC
NO
C