Installation and Maintenance Instructions for
B400 & B700 ASHCROFT® Snap Action
Switches for Pressure Control
B400 DIMENSIONS
4.00
101.6
4.00
101.6
2.55
64.9
Ø .28
7.1
X3 HOLES
2.55
64.9
1.25
31.8
.25
6.4
1.25
31.8
.25
6.4
2.75
69.9
3.31
84.1
5.11
129.8
3/4 NPT
FEMALE
3.31
84.1
2.75
69.9
3/4 NPT
FEMALE
3.25
82.6
3.86
97.9
6.46
164
Ø .34
8.6
X2 HOLES
1/4 NPT
FEMALE
1.38
35.2
.50
12.7
2.78
70.6
1/4 NPT
FEMALE
3.19
81.1
5.75
146.1
Ø 5.12
130
STANDARD RANGES
15, 30, 60, 100, 200, 400, 600 psi
1000, 3000 psi
30˝Hg vac.-0
2.7 lb
STANDARD RANGES
10, 30, 60, 100, 150 ˝H2O
15˝H2O vac.-15˝H2O
(1.2 kg)
B700 DIMENSIONS
Ø 0.28 x 3 HOLES
(7)
Ø 0.28 x 3 HOLES
(7)
3.58
(91)
5.20
(132)
3.58
(91)
5.20
(132)
0.03
(1)
1.37
(35)
3.62
(92)
Ø 3.90
(99)
6.43
163
1.11
(28)
0.36
(9)
0.50
(13)
0.31
(8)
0.31 (8)
1.37
(35)
3/4 NPT
2 HOLES
1.39
(35)
2.78
(71)
3.50
(89)
Ø 5.12
(130)
0.03
(1)
Ø 3.90
(99)
5.73
(146)
1.93
(49)
4.37
(111)
1.22
(31)
0.32
(8)
0.32
(8)
3.62
(92)
1.8 lb
(.81 kg)
2.18
(55)
1.22 (31)
2.18
(55)
Ø 2.31
58.7
3.25
82.6
BRACKET WHEN
"XBP" VARIATION
REQUIRED
3.50
88.9
2.51
63.8
Ø .28
7.1
X3 HOLES
3/4 NPT 2 HOLES
Ø 0.34 X 2 HOLES
(9)
0.36
(9)
1.93
(49)
5.62
(143)
1/4 NPT FEMALE
1/4 NPT FEMALE
2.31
(59)
4.37
(111)
3.06
(78)
2.7 lb
BRACKET WHEN
REQUIRED "XBP"
VARIATION
INTRODUCTION
The Ashcroft pressure switch is a precision built agency
approved control device which features a mechanical snap
action switch. Controllers are available for operation on pressure or vacuum with fixed or variable differential. Also manual
reset types for operation on increasing or decreasing pressure.
The manual reset types remain tripped until reset by pressing a
button on top of the enclosure. Standard electrical switch is
SPDT, available with various electrical characteristics. Two
SPDT switch elements mounted together are available except
on variable Deadband and manual reset types. Various wetted
material constructions for compatibility with a range of pressure
media may be obtained.
The Ashcroft snap action 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
(1.2 kg)
left with internal components exposed. During installation insure
that covers are in place and conduit openings are closed except
when actually working on the control.
MOUNTING B400 AND B700 SERIES
Three holes external to the enclosure for surface mounting.
Location of these holes is shown on the general dimension drawing. They may also be mounted directly on pressure line using
the pressure connection. When tightening control to pressure
line, always use the wrench flats or hex on the lower housing.
ELECTRICAL CONNECTIONS
Remove cover
B400 Series – two screws hold cover to enclosure
B700 Series – cover unscrews
CONDUIT CONNECTIONS
Note – It is recommended that Teflon tape or other sealant be
used on conduit, bushing or plug threads to ensure integrity of
the enclosure.
© 2015 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&M009-10008-10/00 (250-2246E) 06/15
Installation and Maintenance Instructions for
B400 & B700 ASHCROFT® Snap Action
Switches for Pressure Control
B400 Series standard – one 3⁄4˝ NPT conduit hole right side.
B700 Series standard – two 3⁄4˝ N PT conduit holes with one
permanent plug. NEMA 7 & 9 enclosures require proper conduit
seals and breathers as per the National Electrical Code.
label affixed to the inside of the control enclosure. When setpoint has been achieved raise and lower pressure to insure that
setpoint is correct.
B400 SERIES
SPDT – Wire directly to the switch according to circuit requirements. On controls with pilot lights wire lights according to circuit diagram on inside of cover. See special wiring instruction
tag for single switches with two pilot lights and dual switches
with one or more lights.
When performing calibration or changing the setpoint, the setpoint
locking screw should be loosened before turning the setpoint
adjusting nut. Once calibration is complete, re-tighten the setpoint locking screw.
B400 & B700 Series – XJL variation – two 3⁄4˝ NPT conduit
holes with two 3⁄4˝ to 1⁄2˝ NPT reducing bushings.
B400 Series – XJK variation – two 3⁄4˝ NPT conduit holes.
SETPOINT LOCKING SCREW (B400 ONLY)
Once setpoint has been determined, tighten setpoint locking
screw using a 5/64˝ allen (hex) wrench. Do not over torque;
setpoint locking screw only needs to be hand tight.
2 SPDT – Dual switching elements consist of two SPDT switchTERMINAL BLOCK
SWITCH A
3
2
1
1
2
3
C
Setpoint
Locking
Screw
TERMINAL BLOCK
SWITCH B
NO
NC
NC
NO
es mounted together in a bracket. Switches are calibrated to
have simultaneous operation within 1% of range either on
increasing or decreasing pressure but not in both directions.
Wire directly to the front and rear switch according to circuit
requirements. Leads are provided on rear switch color coded as
follows:
Common
– White
Normally Closed – Red
Normally Open – Blue
See SPDT instructions for pilot light hook-up.
C
When hermetically sealed switch elements(s) are supplied, the
lead color coding is as follows:
Common
– White
Normally Closed – Red
Normally Open – Blue
B700 SERIES
SPDT – Wire directly to the switch according to circuit requirements.
2 SPDT – Wire to front switch terminal block (left) and rear
switch terminal block (right) as marked. Strip insulation 5⁄16˝,
insert in proper terminal connector and tighten clamping screw
to secure.
ADJUSTMENT OF SETPOINT
B400 & B700 Series – A single setpoint adjustment nut (7⁄8˝) is
located centrally at the bottom on the inside of the enclosure.
For accurate setpoint calibration, mount the switch on a calibration 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 convenient
changes in pressure.
As received, the pressure switch will normally be set to
approximately 90% of the indicated range. Pressurize the
system to required setpoint and turn the adjustment nut until
switch changes mode. Direction of turning is indicated on a
After installation of the control replace cover to insure electrical
safety and to protect internal parts from the environment.
B450 and B750 VARIABLE DEADBAND SWITCHES
Deadband is varied by rotating the wheel on the precision
switch. When viewed from the front of the enclosure, rotation to
the left increases deadband – rotation to the right decreases
deadband. Letters on the wheel may be used as a reference.
Deadbands obtainable will vary from 0.5% to 9% of pressure
range depending on range segment and type of diaphragm.
ADJUSTMENT OF SETPOINT
As received, the pressure switch will normally be set to approximately 90% of range. Rotate the wheel on the MICRO SWITCH
all the way to the right; this will provide smallest deadband.
Pressurize the system to the required setpoint and turn the
adjustment nut until the switch changes mode. Lower the
pressure to reset the switch. Rotate the wheel on the MICRO
SWITCH until the desired deadband is obtained. The upper
setpoint will be changing upward with this adjustment. Lower
the pressure to reset the switch. Then increase the pressure to
the desired setpoint and turn the adjusting nut until the switch
changes mode. Lower the pressure and check resetpoint and
deadband.
Note – As indicated above, adjustment of setpoint is made by
use of 7⁄8˝ nut. Precision switch element mounting
screws and bracket adjusting screw are factory sealed
and should not be tampered with.
Note – Since vacuum models are already above setpoint at
atmosphere, the Normally Open (NO) circuit will be
closed as received.
Recommended Practices
Ashcroft recommends regular inspection of the operation and
setpoint of the switch in critical applications to prevent issues
that could cause severe damage to personnel or property.
© 2015 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&M009-10008-10/00 (250-2246E) 06/15