Installation and Maintenance Instructions for
T400 & T700 ASHCROFT
®
Snap Action
Switches for Temperature Control
© 2017 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&M009-10006-10/00 (250-2230G) 12/17
0.22 (6)
3
.32
(84)
3.26 (83)
0.28 (7) X 3 HOLES
4.03 (102)
Ø2.31 (59)
4.61
(
117)
2.31
ACTIVE BULB
L
ENGTH
(59)
2.77
(70)
2.27
(58)
1.25
(32)
0.25
(
6)
3
.00
(76)
Ø0.37
(9)
“L”
2.50
(64)
2.00
(51)
3/4 NPT
Ø
0.22
(6)
3
.32
(84)
3
.26 (83)
Ø 0.28 (7) X 3 HOLES
4.03 (102)
Ø
2.31 (59)
4.61
(117)
2
.77
(70)
2.27
(
58)
1.25
(32)
0.25
(6)
Ø0.37
(9)
2.00
(
51)
1.31
(
33)
2
.31
ACTIVE BULB
LENGTH
(59)
“S”
3
/4 NPT
1
/2 NPT MALE
7
/8 HEX
T
400 REMOTE MOUNT
T
400 DIRECT MOUNT
T
700 REMOTE MOUNT
T
700 DIRECT MOUNT
5.20
(
132)
3.61
(92)
2.18
(
55)
0
.32
(8)
4
.37
(111)
1.37
(35)
Ø
0.28 x 3 HOLES
(7)
2
.31
(59)
5.23
(133)
1.93
(49)
2.31
ACTIVE BULB
LENGTH
(59)
Ø3.90
(
99)
0.03
(1)
3.58
(
91)
0.31 (8)
1.22 (31)
2.50
(64)
“L”
3.00
(
76)
Ø0.37
(9)
3/4 NPT 2 HOLES
5
.20
(132)
3.60 (91)
2.18
(55)
4.37
(111)
1.37
(35)
Ø 0.28 x 3 HOLES
(7)
1.93
(49)
0.32
(8)
5.23
(133)
2.31
(59)
Ø3.90
(99)
0.03
(1)
3.58
(91)
0.31
(8)
1
.22
(
31)
0.37
(9)
2.31
ACTIVE BULB
(59)
1.31
(
33)
“S”
1/2 NPT MALE
3/4 NPT 2 HOLES
7/8 HEX
LENGTH
STEM LENGTH – INCHES
S 2.75 4.0 6.0 9.0 12.0
LINE LENGTH – FEET
L 5.0 10.0 15.0 20.0 25.0
3.5 lbs.
2.5 lbs.
4.5 lbs.
3.7 lbs.
INTRODUCTION
The Ashcroft
®
temperature switch is a precision built U.L. and
C.S.A. approved control device which features a mechanical
snap action switch. Controllers are available for operation on
temperature with fixed or variable differential. Also, manual reset
types are available for operation on increasing or decreasing
temperature. The manual reset types remain tripped until reset
by pressing a button on the top of the enclosure. The standard
electrical switch is SPDT and is available with various electrical
characteristics. Two SPDT switch elements mounted together
are available except on variable deadband and manual reset
types. Bulb material is stainless steel.
The Ashcroft snap action temperature switch is furnished in the
standard NEMA 4/4X and explosion proof NEMA 7 and 9 enclo-
sure styles. Both enclosures are epoxy coated aluminum castings.
INSTALLATION
These controls are precision instruments and should never be
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. Good piping practice re-
quires the use of a thermowell for installation where pressure
may be applied to the thermal system. The thermowell provides
protection against physical damage as well as corrosive effects
of media flow. Use of a thermowell also facilitates removal of the
bulb from the process line without disturbing the process. Stan-
dard thermowell materials include brass, steel and stainless
steel; other materials are available upon request. Selection
should be based on corrosion resistance requirements and
process pressure.
Installation and Maintenance Instructions for
T400 & T700 ASHCROFT
®
Snap Action
Switches for Temperature Control
© 2017 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&M009-10006-10/00 (250-2230G) 12/17
MOUNTING T400 AND T700 SERIES
There are three holes external to the enclosure for surface
m
ounting. Location of these holes is shown on the general di-
mension drawing.
A. Direct - Mounted Controls
These controls have a
1
⁄
2 NPT threaded adapter and may be at-
tached directly or indirectly by means of a thermowell to equip-
ment to be controlled. When installing or removing control
always use the wrench flats or hex above the threads. Do
not twist the housing.
B. Remote Mounted Controls
Two types of union bushings are available to install a remote
mounted bulb into a thermowell or other
1
⁄
2 NPT threaded hole.
A non-pressure tight type consists of a bushing, split grommet
and compression nut. To use this, the bulb is inserted through
the nut and the split grommet is slipped into the capillary be-
tween the compression nut and the bushing. After positioning
the bulb as desired tighten the nut to the bushing. This will lock
the capillary at the desired location. The pressure tight type is
clamped to the bulb after insertion by tightening the compression
nut. To use
this, the union bushing is screwed into the
1
⁄
2 NPT threaded hole.
The compression nut and sleeve are slipped onto the bulb which
is then inserted into the union bushing.
The bulb is then positioned and the compression nut is hand
tightened pus 2
1
⁄
4 turns. This will lock the capillary at the
desired location.
ELECTRICAL CONNECTIONS
Remove cover
T400 Series – two screws hold cover to enclosure
T700 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.
T400 Series standard – one
3
⁄
4 NPT conduit hole right side.
T700 Series standard – two
3
⁄
4 NPT conduit holes with one per-
manent plug. NEMA 7 & 9 enclosures require proper conduit
seals and breathers as per the National Electrical Code.
T400 & T700 series – XJL variation –
3
⁄
4 to
1
⁄
2 NPT reducing
bushing supplied.
T400 Series – XJK variation – two
3
⁄
4 NPT conduit holes.
T400 SERIES
SPDT – Wire directly to the switch according to circuit require-
ments. 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.
TERMINAL BLOCK
F
RONT SWITCH
TERMINAL BLOCK
R
EAR SWITCH
NC
NO
C
N
C
N
O
C
Setpoint
Locking
Screw
2-SPDT – Dual switching elements consist of two SPDT switches
m
ounted 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
W
hen hermetically sealed switch element (s) are supplied, the
lead color coding is as follows:
Common – White
Normally Closed – Red
Normally Open – Blue
T700 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.
SETPOINT LOCKING SCREW (T400 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.
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 set-
point locking screw.
After installation of the control replace cover to insure electrical
safety and to protect internal parts from the environment.
ADJUSTMENT OF SETPOINT
T400 & T700 Series – A single setpoint adjustment nut (
7
⁄
8˝) is
located centrally at the bottom on the inside of the enclosure.
The bulb of the control should be immersed in a bath at the
desired setpoint temperature. Optimum performance will be
obtained if the bulb is fully immersed. Allow five minutes for
initial stabilization.
Installation and Maintenance Instructions for
T400 & T700 ASHCROFT
®
Snap Action
Switches for Temperature Control
© 2017 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&M009-10006-10/00 (250-2230G) 12/17
As received, the temperature switch will normally be set to
a
pproximately 90% of the indicated range. After stabilization,
turn the adjustment nut until switch changes mode. Direction of
turning is indicated on a label affixed to the inside of the control
enclosure. When setpoint has been achieved raise and lower
temperature to insure that the setpoint is correct.
After installation of the control replace cover to insure electrical
safety and to protect internal parts from the environment.
T450 and T750 VARIABLE DEADBAND SWITCHES
D
eadband 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 decreased
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.
ADJUSTMENT OF SETPOINT
As received, the temperature 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 dead-
band. Increase bath temperature to the required setpoint and
turn the adjustment nut until the switch changes mode. Lower
the bath temperature 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 bath temperature to reset the switch. Raise the bath
temperature to the desired setpoint and turn the adjusting nut
until the switch changes mode. Lower the bath temperature and
check reset point and deadband.
T428 & T429 MANUAL RESET SWITCHES
Route wire leads from switch terminals so as not to interfere with
or touch reset button.
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.
Installation and Maintenance Instructions for
T400 & T700 ASHCROFT
®
Snap Action
Switches for Temperature Control
© 2017 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&M009-10006-10/00 (250-2230G) 12/17
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