Ashcroft GD User Manual
Installation and Maintenance Instructions
1 2 3
1 2 3
LEFT SWITCH
TERMINAL BLOCK
RIGHT SWITCH
TERMINAL BLOCK
SERVICE LEADS TOTHESETERMINALS
NC
NO
C
5.68
(144)
0
.38
(10)
4
.17
(106)
5.61
(142)
2
.10
(53)
1.60
(41)
1
.93
(49)
3.48
(88)
0.15
(
4)
L
4
.78
(121)
2.64
(
67)
0.25
(6)
2.50
(64)
Ø
2 . 31
(5 9)
1 /4NPT
LOW
H
PORT
FEMALE
PRESSURE
1/4 NPT
P
ORT
FEMALE
P
RESSURE
HIGH
3/4 NPT FEMALE
C
ONDUIT ADAPTER
for ASHCROFT®G-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
vailable with a SPOT switch with various electrical ratings.
a
Several wetted material constructions for compatibility with
pressure media may be obtained.
Series GD-S switches have a fixed deadband which will be
within the limits noted on the nameplate.
Series GD-D switches may be set to operate simultaneously
or up to 85 percent of the range apart. The dead band of each
s
witch will be within the limits noted on the nameplate.
ies GD-A switches may be set to operate with any dead-
Ser
band within the limits shown on the nameplate.
MOUNTING
The “G” Series ASHCROFT®snap action differential pressure
switch has a NEMA-4X enclosure made of 316 stainless steel.
Two holes in the bracket supplied are used to surface mount
the control. Location of these holes is shown on the general
wings. An optional pipe mounting bracket is also
a
dimension dr
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.”
© 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&M009/10020-10/00 (250-2892) AMR 12/07
4.6 lbs. (2.1kg)
STANDARD RANGES
30, 60, 90, 200, 400 psid
CONDUIT CONNECTIONS
One 3⁄
4 NPSM conduit adapter of 316 stainless steel is provided.
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
, held in place by four screws.
er
v
e co
v
Remo
On all units e
xcept one with ter
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).
minal blocks – wire directly to
Installation and Maintenance Instructions
A
B
0
20
40
60
0
20
40
60
for ASHCROFT®G-Series Snap Action
Switches for Differential Pressure Control
ETPOINT ADJUSTMENTS
S
Setpoints are changed by means of the setpoint adjusters.The
GD-S single switch has one adjuster and the GD-A adjustable
deadband and GD-D dual switches each have two adjusters. On
switches with two adjusters, the one on the left is referred to as
“A” and the right one is referred to as “B”; see illustration.
Setpoints can be adjusted from 20 to 100 percent of full range
on increasing pressure.
SERIES GD-S SINGLE SWITCH
Remove cover.For setpoint adjustment on either increasing or
decreasing pressure to within ±1% of nominal range, mount the
switch on a calibration stand and use a suitable reference such
as an ASHCROFT
®
Duragauge or test gauge.Monitor switch
with a light or meter.
Apply
Low pressure. Then apply High pressure equal to the
low pressure plus the differential pressure setpoint.If setpoint is
on increasing differential pressure, turn adjuster so that switch
operates (if common – normally closed circuit is being monitored light goes off). If setpoint is on decreasing differential pressure, turn adjuster so that switch resets (if common – normally
closed circuit is being monitored light comes on).When the setpoint has been achieved, raise and lower the high pressure to
ensure that the setpoint is correct.
The deadband (difference between the operate and reset
pressures) may be verified at this time to be between the values
noted on the nameplate label.
SERIES GD-D DUAL SWITCH
Remove cover.For setpoint adjustment to within ±1% of nominal
range, mount the switch on a calibration stand and use the suitable reference such as an ASHCROFT
®
Duragauge or test
gauge. Monitor switch with a light or meter.
Apply
Low pressure. Then apply High pressure to the higher
f the two required setpoints.Turn adjuster “B” until the switch
o
perates or resets as required. See discussion of increasing or
o
ecreasing differential pressure setpoints and deadband verifi-
d
cation under Series GD-S Single Switch.When the setpoint has
been achieved, raise and lower the
the
High pressure to the lower setpoint differential pressure and
High pressure.Then reduce
turn adjuster “A” until the switch operates or resets as required.
Verify this setpoint by raising and lowering the
Now increase the
High pressure to the higher setpoint and
High pressure.
make final adjustment on “B.”
SERIES GD-A ADJUSTABLE DEADBAND SWITCH
Remove cover.Adjuster “B”controls the operating point of the
switch on increasing pressure.Adjuster “A”controls the re-setpoint
of the switch on decreasing pressure.
For accurate setpoint adjustment, mount the switch on a calibration stand and use a suitable reference such as an
ASHCR
light or meter.Apply
OFT
®
Dur
agauge or test gauge. Monitor switch with a
Low pressure. Then apply High pressure to
the required setpoint pressure.
Tur n adjuster “B” until switch operates.Then lower differential
pressure to the re-setpoint and turn adjuster “A”until the switch
resets. Now increase pressure to the operating point and make
final adjustment on “B.” Raise and lower pressure to ensure that
the setpoint and re-setpoint are correct.
SOME PRECAUTIONS TO OBSERVE
Do not loosen the screws holding the precision switch element(s)
or mounting bracket in place.
Nameplate
PROOF pressure should not be exceeded. Intermittent operation up to proof pressure is permissible, however,
some change of setpoint may be noted.
Operation and correct setpoint actuation should be
routinely tested.
ord, CT 06614-5145, USA, Tel: 203-378-8281, Fax: 203-385-0499, www.ashcroft.com
atf
2007 Ashcroft Inc., 250 East Main Street, Str
©
All sales subject to standard terms and conditions of sale. I&M009/10020-10/00 (250-2892) AMR 12/07
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