Chromalox PK405-18 - Manual (Page 2)

GENERAL
MOUNTING
NOTICE: Type AR Thermostats are designed for temperature con-
trol 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 pro-
vided 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.
Enclosure – The control enclosure and cover assembly is of heavy-
gauge electrical grade plastic on NEMA-I models.
Moisture resistant (LT) models have enclosure and cover assembly
made of heavy gauge cast aluminum.
Power Supply –
FIRE/ELECTRIC SHOCK HAZARD. Use AC supply only.
Thermostat is not DC rated.
Control Range – The following temperature ranges are available:
0° to 100°F 200° to 550°F
60° to 250°F 300° to 700°F
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 differential
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 similar
equipment, an appropriate packing gland is available as an optional
part. (Model Numbers 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.
Note: Do not mount control where it will be subject to vibration,
shock, grease, dust, lint or corrosive vapors. Do not mount adjacent
to a large magnetic contactor, as vibration and shock will cause ther-
mostat to interact erratically - resulting in chattering of the contactor.
The air temperature in and around the control enclosure should be
kept as near to normal room temperature as possible...never above 150°F.
5"
5/16" Dia.
Mounting Lugs
5-7/8" Dia.
7/32" Dia.
(4)
Mounting Holes
3-7/8" Dia.
2-7/16" Dia.
(2)
NEMA-I Models LT Models
1”
Do Not
Bend or Kink
Crimped End
1/2”
Rod
Figure 3
(Sensing Bulb)
Figure 4
(Capillary Tube)
1. To facilitate adjusting and reading the thermostat, knob setting
must be mounted in a vertical position only.
2. Use sheet metal or wood screws through the 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 sensitive Style 9 bulbs should be used for con-
trolling air temperatures or pipe line heating.
Note: If material in contact with bulb or capillary is corrosive, a pro-
tective well should be used. Protective wells are available as an
optional part. Check factory.
4. CAUTION –
A. Bending or deforming sensing bulb will alter control calibra-
tion – requiring recalibration after installation. See CALI-
BRATION 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 temperature dif-
ferential. Minimum capillary tube bending diameter 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.
ELECTRIC SHOCK HAZARD. Disconect all power to
heater before installing or servicing thermostat.
Failure to do so could result in personal injury or
property damage. Thermostat must be installed by a
qualified person in accordance with the National
Electrical Code, NFPA 70.
1. Electrical wiring must be installed in accordance with National
Electrical Codes or local codes.
CAUTION: Use copper conductors only.
NEMA-I Models –
A. Entrance for wiring is provided by two 1/2” conduit holes in
end of base plate.
B. If control is a “–KC” model (knob cover), remove knob cover
as in Figure 5.
C. Set thermostat knob to OFF position and then remove knob by
lifting knob from shaft (see Figure 6).
D. Loosen two screws from end of base plate and remove ther-
mostat cover (see Figure 7).
WIRING