Installation and Maintenance Instructions
for N Series Electronic Pressure Switch
3.31
3.26
5.62
INDICATING LEDS
NOTE:THIS VIEW SHOWN
WITH COVER REMOVED
TERMINAL
BLOCK
GROUND
SCREW
DEADBAND
ADJUSTMENT
KNOB
SETPOINT ADJUSTMENT KNOB
SP INCR CW
DB INCR CW
AC
AC
NC
C
NO
1.26
3.0
3/4 NPT
1/4 NPT MALE
PRESSURE CONNECTION
(143)
(84)
(83)
(32)
(7
SP INCR CW
DB INCR CW
3.62
4.37
INDICATING
LEDS
TERMINAL BLOCKS
GROUND SCREW
SETPOINT
ADJUSTMENT
KNOB
DEADBAND
ADJUSTMENT
KNOB
AC AC NC C NO
6.55
3.67
3.96
1.25
3/4 NPT
FEMALE
NOTE:THIS VIEW SHOWN
WITH COVER REMOVED
1/4 NPT MALE
PRESSURE CONNECTION
(92)
(111)
(101)
(32)
(166)
(93)
N4
N7
Ranges –
60, 100, 200, 300, 500, 750, 1000, 2000, 3000, 5000, 7500,
10,000, 15,000, 20,000 psi
1.8 lb
(.81 kg)
INTRODUCTION
The Ashcroft
®
pressure switch is a precision built control device
which features an Ashcroft
®
K-Series polysilicon thin film pres-
sure sensor (Transducer). Pressure switches are available for
operation on pressure with fixed or variable deadband (differen-
tial). The standard electrical switch is a SPDT sealed mechani-
cal relay. The wetted materials are 17-4PH and 316 stainless
steel. The Ashcroft
®
pressure switch is furnished in the standard
NEMA 4 and explosion proof NEMA 7/9 enclosure styles. Both
enclosures are epoxy coated aluminum castings.
INSTALLATION
These controls are precision instruments and should never be
left with internal components exposed. After installation, ensure
that the covers are in place and the conduit openings are
closed.
MOUNTING N4 & N7 SERIES
There are three holes external to the enclosure for surface
mounting. The locations of these holes are shown on the gener-
al dimension drawing. The controls may also be mounted direct-
ly on the pressure line using the pressure connection. When
tightening the control to the pressure line, always use the
wrench flats or the hex on the lower housing.
ELECTRICAL CONNECTIONS
WARNING: Cover with display has a ribbon cable connected to the
cover that can come loose. Take care when opening.
Remove cover.
N4 Series – Two screws hold cover to enclosure
N7 Series – Cover unscrews
CONDUIT CONNECTIONS
Note: It is recommended that Teflon tape or other sealant be
used on the conduit, bushing or plug threads to ensure
the integrity of the enclosure.
N4 Series Standard – One
3
⁄4 NPT conduit hole right side.
N7 Series Standard – Two
3
⁄4 NPT conduit holes with one per-
manent plug. NEMA 7/9 enclosure require proper conduit
seals and breathers as per the National Electrical Code.
N4 and N7 Series – XJL Variation –
3
⁄4 NPT conduit holes with
3
⁄4 to
1
⁄2 NPT reducing bushings.
N4 Series – XJL Variation –
Two 3⁄4 NPT conduit holes.This option is recommended when
ordering 4-20mA output.
N4 & N7 SERIES
SPDT – Wire directly to the terminal block according to circuit
requirements. For 120Vac 60 Hz switch, wire power lines to
terminal marked ac. For 24 Vdc switch, wire positive power line
to terminal marked 24Vdc + and wire negative power line to
terminal marked 24Vdc –.
N4 & N7 SERIES
Adjustment of Setpoint
A 25 turn adjustment potentiometer is located at the upper right
corner on the inside of the enclosure.
For accurate setpoint calibration, mount the switch on a cali-
bration stand, a pump or catalog no. 1305 deadweight gauge
tester. A suitable reference standard such as an Ashcroft
Duragauge or test gauge is necessary to observe changes in
pressure.
© 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&M009-10026-6/04 (250-B145-01) Rev. 3 AMR 05/10
N4
TERMINAL BLOCK
N7
TERMINAL BLOCK
4-20mA
OUTPUT OPTION
Setpoint Potentiometer
Deadband
Potentiometer
Ground Screw
N4 Terminal Block
INDICATING LED’S
GREEN Normally Open
RED Normally CLOSED
4-20mA Output Option
(2 pages)
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