Thermowells0 pages

Data sheet
Date
Page

THERMOWELL
01/2013
1 of 5

THERMOWELLS
CONSTRUCTION FROM BARSTOCK OR FABRICATED
A thermowell is a thermally conductive socket recommended to:
•
•

Protect the delicate instrument sensing elements against corrosive effects.
Permit instrument interchange or calibration check without disturbing or closing
down the process.

Thermowells are available for high pressures, high temperatures and high velocity
applications. Selected on the basis of pressure, temperature, flow, vibration and
corrosion service parameters.

ATEX approvals available under our PCI TEMA brand.

DESCRIPTION
F - THE INSTRUMENT CONNECTION
It is usually a female thread axially aligned with the bore into which the instrument mounting
threads or capillary bushing is screwed but other connections can also be supplied.
BORE
It is the inside cylindrical diameter of a thermowell. The 1/4", 3/8" and 1/2” nominal bore are
thermowell standard.
S - THE INSTRUMENT INSERTION LENGTH
Commonly called the «S» or the «L» dimension, it is the length from the top oft the mounting threads
of a thermometer to the end of its stem or from the threads of a union bushing on a fixed extension
or a capillary, to the end of the extension.
E - SHANK CONFIGURATION
It is the shape of that portion of a thermowell that is inserted into the process. The tapered shank is
recommended as opposed to a stepped or straight shank due to the superior strength and vibration
resistance.
T - LAGGING EXTENSION
Show as «T», it is used when the vessel or pipe into which the thermowell is inserted, is insulated.
This is the extra length between the process connection and the instrument connection of a
thermowell, which is determined by the insulation thickness. The standard lagging extension is 3”
except it is 2" for the thermowells with 2-½” «U» dimensions. Other are available on request
P - THE PROCESS CONNECTION
It is that portion of the thermowell which provides the mechanical connection with the vessel or
pipe. These connections can be integral male thread, prepared surface for welding flanges for
mechanical pressure seals, or combinations thereof . Thermowell standard process threads are ½",
¾" and 1" NPT. Standard flanges are raised face or ring joint types, dimensioned to ASA B 16.5;
standard flange sizes are 1", 1- ½” and 2” with rating from 150 lbs to 900 lbs. Standard weld in
sizes are for ¾" and 1" nominal pipe. Other size process connections can be provided on request.
U - THE THERMOWELL INSERTION LENGTH
It is commonly called the «U» dimension, it is that portion of the shank from the process connection
to the tip of the shank which is inserted into the process area.

_______________________________________________________________________________________________
PCI (Process System Solutions) Ltd, Unit 7 Slaidburn Crescent, Southport, Merseyside, PR9 9YF, UK,
Tel: +44 (0) 1704 509090, Fax: +44 (0) 1704 509091,
email: sales@pci-instruments.com, Website: www.pci-instruments.com