Chromalox PK407-4 - Manual (Page 2)

GENERAL
NOTICE: Type AR Thermostats are designed for temperature
control service only. Because they do not fail safe, they should not
be used for temperature limiting duty.
The system designer is responsible for the safety of
this equipment and should install adequate back-up
controls and safety devices with their electric heat-
ing equipment. Where the consequences of failure
could result in personal injury or property damage,
back-up controls are essential.
Principle of Operation — Control action of these thermostats is
provided through the principle of liquid volume change. With a
variation in temperature, the liquid in the sensing bulb expands or
contracts, causing a bellows to actuate the switching mechanism.
Housing — The control housing and cover assembly is of heavy-
gauge electrical grade plastic.
FIRE/ELECTRIC SHOCK HAZARD. Use AC supply only.
Thermostat is not DC rated.
Control Range — The following temperature ranges are available:
Fahrenheit
60° to 250° 200° to 550°
Process Temperature Differential — is variation in controlled
process temperature between maximum, when thermostat turns
OFF and minimum, when thermostat turns ON. This spread in
temperature may be minimized by —
1. Making sure control is mounted to vertical surface (see Step 1,
MOUNTING section).
2. Avoiding excess heating capacity (oversized heaters).
3. Locating control sensing bulb in optimum position between
heat source and work.
In general, it is difficult to predict the actual operating differ-
ential of a given process. Temperature differential may be as low
as 4°F for low range controls to as high as 17°F for higher range
controls since the differential is a percentage function of the dial
range.
Packing Glands — If a sealed or leak-proof connection is required
at the point where the capillary enters the oven, tank, pipe or simi-
lar equipment, an appropriate packing gland is available as an
optional part. (Model CCF-25A, CCF-25D or CCF-25E)
FIRE/EXPLOSION HAZARD. This thermostat is not
intended for use in hazardous atmospheres where
flammable vapors, gases, liquids or other com-
bustible atmospheres are present as defined in the
National Electrical Code. Failure to comply can result
in personal injury or property damage.
MOUNTING
Note: Do not mount thermostat where it will be subject to vibra-
tion, shock, grease, dust, lint or corrosive vapors. Do not mount
adjacent to a large magnetic contactor, as vibration and shock will
cause thermostat to interact erratically — resulting in chattering of
the contactor.
The air temperature in and around the thermostat enclosure
should be kept as near to normal room temperature as possible...
never above 150°F.
1. Thermostat must be mount-
ed in a vertical position only.
2. Use sheet metal or wood
screws through the four 7 /
32
”
diameter mounting holes in
baseplate to mount control
(see Figure 2).
3. For controlling platen or die
temperatures, insert entire
sensing bulb into drilled holes
selected for snug slip fit.
The longer, more sensi-
tive Style 9 bulbs should be
used for controlling air tem-
peratures or pipe line heating.
4. NOTICE:
A. Bending or deforming
sensing bulb will alter
control calibration —
requiring recalibration after installation. See CALIBRA-
TION section, page 3. If necessary, Style 9 bulbs can be
coiled to 1” I.D. (see Figure 3).
B. Do not kink capillary tube. The resulting constrictions in
fluid flow can destroy control function or broaden temper-
ature differential. Minimum capillary tube bending diame-
ter is 1/2” I.D. (see Figure 4).
C. Any deformations of bulb or capillary that result in leakage
of fluid from control renders control inoperative.
D. Avoid passing control capillary tube through zones whose
temperature is in excess of controlled process temperature.
Erratic control or destruction of control function may result.
Figure 2
Figure 3
(Sensing Bulb)
Figure 4
(Capillary Tube)
1”
1 /
2
”
Rod
Do Not Bend or
Kink Crimped End