Honeywell 107324A Benutzerhandbuch

7

68-0040—04

An immersion well consists of a metal tube, called the well 

shell, closed on one end. A well spud externally threaded to fit 

standard boiler tappings is welded or brazed on the open end. 

See Fig. 1. The well is inserted into the tank and the 

temperature sensing bulb is inserted into the well. The sensing 

bulb never touches the controlled medium. Because the well 

conducts heat rapidly, the bulb responds quickly and 

accurately to temperature changes in the controlled medium.

An immersion well protects the temperature sensing bulb from 

mechanical damage or damage due to chemical interaction 

with the controlled medium. Also, a well permits removal of the 

sensing bulb for testing or control replacement without draining 

the system. The threaded fitting of the well spud provides a 

tighter seal than a packing nut applied to the capillary.

The immersion well material must conduct heat readily and 

resist corrosive and electrolytic action (especially in brine 

solutions and when the well is a different material than the 

container). The material must also resist fluid contamination 

from chemical reaction with the well and withstand high 

temperatures. Most Honeywell immersion wells are copper 

because of its high conductivity. Stainless steel, mild steel and 

Monel wells are also available for applications requiring higher 

maximum temperature and pressure ratings or greater 

corrosion resistance. Some copper wells are available with a 

plastic sleeve over the tube to reduce electrolytic and corrosive 

activity.

Major factors in selecting well size are:

—

size of the boiler tapping.

—

bulb diameter.

—

insulation depth.

—

insertion length.

Immersion wells are available to fit standard 1/2-14 NPT and 3/

4-14 NPT tappings. Sensing bulbs are 3/8, 1/2 or 11/16 in. in 

diameter with well shells designed to fit these diameters. The 

bulb should fit tightly in the shell. If the bulb fits loosely, fill the 

space between the shell and bulb with heat-conductive 

compound to ensure maximum heat transfer. Many Honeywell 

temperature controllers ship with heat-conductive compound; 

available in 4-oz cans and 1/2-oz single-application tubes. See 

Table 4.

he nominal length of the spud, including the full length of the 

threads and the hex, defines the insulation depth. Depending 

on the characteristics of the tapping, 1/8 to 1/2 in. of the 

Bulb shield assembly

Shields bulb from weather; 

less mounting screws and 

split plug.

6 in. (152 mm) long; holds 3/8 

in. and 1/2 bulbs.

Shields bulb from weather; 

includes mounting screws 

and 33578 Split Plug.

7 in. (118 mm) long, clip holds 

3/8 in. bulb.

Pipe Strap

Fastens bulb to outside of 

pipe.

4-1/2 in. (114 mm) long; used 

with up to 3/4 in. OD pipe.

M17284

M17285

M17286