Ashcroft LT - Temperature Switches - Manual

Installation and Maintenance Instructions
for ASHCROFT
® L-Series Snap Action
Switches for Temperature Control
(105)
2.25
(57)
2.50
(64)
0.25
(6)
3.47
(88)
2.06
(52)
1.21
(31)
0.38
(10)
3.94
(100)
1.31
(33)
“S”
Ø 0 . 3 7
( 9 )
2 . 3 1
ACTIVE BULB
LENGTH
( 5 9 )
3 . 2 6
( 8 3 )
6 . 0 9
( 1 5 5 )
3 /4 NPT
7/8 HEX
1 /2 NPT MALE
4 . 1 2
2.31
ACTIVE BULB
LENGTH
(59)
2.06
(52)
0.38
(10)
3.94
(100)
3.26
(83)
“L”
3 . 0 0
( 76 )
2 . 5 0
( 6 4 )
Ø 0 . 3 7
( 9 )
1 . 2 1
( 3 1 )
6 . 0 9
( 1 5 5 )
3 /4 NPT
4 . 1 2
( 1 0 5 )
0 . 2 5
( 6 )
2 . 2 5
( 5 7)
2 . 5 0
( 6 4 )
Direct Mount
Remote Mount
3.5 lbs.
4.5 lbs.
2 3 ⁄
4
4 6 9 12
(70) (102) (152) (229) (305)
STEM LENGTH (S)
5 10 15 20 25
LINE LENGTH
IN.
MM
FT.
© 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&M009-10018-10/00 (250-2873) AMR 12/-07
OPERATION
The ASHCROFT
® temperature 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. Bulb material
is stainless steel.
Series LT-S switches have a fixed deadband which will be
within the limits noted on the nameplate.
Series LT-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 LT-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 temperature switch has a
NEMA-4 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.
Good piping practice requires the use of a well for installation,
where pressure may be applied to the thermal system, for pro-
tection against physical damage as well as corrosive effects of
media flow. Use of a well also facilitates removal of the bulb
from the process line without disturbing the process. Standard
well materials include brass, and stainless steel; other materials
are available on application. Selection should be based on cor-
rosion resistance requirements and process pressure.
A. STEM MOUNTED CONTROLS
These controls have a 1 ⁄
2
NPT threaded adapter and may be
attached directly (or indirectly by means of a thermowell) to
equipment 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 control bulb into a thermowell or other
1 ⁄
2
NPT threaded hole. A non-pressure-tight type consists of a
bushing, split grom-met and compression nut. To use this, the
bulb is inserted through the nut and the split grommet is
slipped into the capillary between the compression nut and
the bushings. After positioning the bulb as desired, tighten
the compression nut to the bushing. This will lock the capil-
lary at the desired location. The pressure-tight type is
clamped to the bulb after insertion by tightening a compres-
sion 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. Bulb is then positioned and compression nut is
hand tightened plus 2
1 ⁄
2
turns. This will lock the bulb at the
desired location.
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.