Chromalox RST PN400-3 User Manual

(Supersedes PN400-2)

PN400-3

RST

161-049178-001

MAY, 1986

4

and

Installation, Operation

RENEWAL PARTS IDENTIFICATION

Type RST and RSTO

Unitary Electric Immersion Heaters

© 2010 Chromalox, Inc.

Specifications – Table A

Tank Heater

Amperes** Adapter Box Dimensions (In.)

Holding Approximate

Temperature “B” No. Net Weight

Capacity Dimensions (°F) kW 240V 480V Model † Height Depth Length Dimension* Tubes (Lbs.)

175 15 37.0 18.5 RST (or) RSTO-21915 8

1

/2 81/4 20 19’ 2 560

8,000

8’ (Dia.) 225 20 49.0 24.5 RST (or) RSTO-21920 8

1

/2 81/4 20 19’ 2 560

Gal.

x 275 25 61.2 30.6 RST (or) RSTO-21925 8

1

/2 81/4 20 19’ 2 560

21’6” 325 30 73.0 36.5 RST (or) RSTO-51530 8

1

/2 81/4 35 15’ 5 1100

375 38 92.4 46.2 RST (or) RSTO-52038 8

1

/2 81/4 35 19’6” 5 1300

10’6” (Dia.)

175 18 44.3 22.2 RST (or) RSTO-31518 8

1

/2 81/4 25 15’ 3 635

10,000

x

225 24 58.7 29.4 RST (or) RSTO-41524 8

1

/2 81/4 30 15’ 4 905

Gal.

15’6”

325 36 87.6 43.8 RST (or) RSTO-61536 8

1

/2 81/4 40 15’ 6 1270

375 45 109.2 54.6 RST (or) RSTO-81545 8

1

/2 81/4 50 14’6” 8 1710

175 20 49.0 24.5 RST (or) RSTO-31720 8

1

/2 81/4 25 17’ 3 695

12,000

10’6” (Dia.) 225 26 63.5 31.7 RST (or) RSTO-41726 8

1

/2 81/4 30 16’6” 4 925

Gal.

x 275 32 78.0 39.0 RST (or) RSTO-51732 8

1

/2 81/4 35 16’6” 5 1135

18’6” 325 40 97.2 48.6 RST (or) RSTO-61740 8

1

/2 81/4 40 17’ 6 1440

375 48 116.4 58.2 RST (or) RSTO-71848 8

1

/2 81/4 45 17’6” 7 1620

175 22 54.0 27.0 RST (or) RSTO-31922 8

1

/2 81/4 25 18’8” 3 725

15,000

10’6” (Dia.) 225 30 73.0 36.5 RST (or) RSTO-41930 8

1

/2 81/4 30 19’ 4 1055

Gal.

x 275 36 87.6 43.8 RST (or) RSTO-51936 8

1

/2 81/4 35 18’6” 5 1230

23’3” 325 45 109.2 54.6 RST (or) RSTO-61945 8

1

/2 81/4 40 19’ 6 1530

375 56 136.0 68.0 RST (or) RSTO-72156 8

1

/2 81/4 45 20’6” 7 1830

175 24 58.7 29.4 RST (or) RSTO-32024 8

1

/2 81/4 25 19’6” 3 755

20,000

10’6” (Dia.) 225 36 87.6 43.8 RST (or) RSTO-42336 8

1

/2 81/4 30 23’ 4 1205

Gal.

x 275 48 116.4 58.2 RST (or) RSTO-52548 8

1

/2 81/4 35 25’ 5 1605

30’10

1

/2” 325 60 145.2 72.6 RST (or) RSTO-62660 81/2 81/4 40 25’6” 6 1790

375 72 174.2 87.1 RST (or) RSTO-72672 8

1

/2 81/4 45 26’ 7 2260

*Heated length is four inches shorter than “B” dimension.
**All amperes based on 3-phase 60 cycle power.
† T suffix letter indicates 7 day 24 hour time clock, F suffix letter indicates flange mounting instead of adaptor box.

3” Schedule 40
Steel Pipe

Immersed Length or “B”
Dimension From End
Of Adaptor Box To
End Of Tubes

GENERAL

The Chromalox Unitary Electric Immersion Heater, Type RST
or RSTO, is a thoroughly engineered pretested package designed
to give years of service vitrually maintenance free and shipped
ready for installation in storage tank. They provide low watt
denisty heating over a large heating surface with precise tempera­ture control for such materials as asphalt, fuel oil, pitch and tar, liq­uid sugar, lube oils, linseed oil, and many other heat sensitive
compounds.

The heating elements, either metal sheath (RST) or open coil
(RSTO) are housed in 3” Schedule 40 carbon steel pipes which are

welded into the tank adaptor box. Once the Unitary Immersion
Heater is welded into your tank, the heating elements are remov­able without draining the tank.

The control panel contains a master circuit-breaker which is
safety-interlocked so the door cannot be opened when the power is
on, two contactors, a two-step indicating thermostat with the tem­perature range of 50 to 400°F*, over-temperature cutout with man­ual reset, control relay, selector switches, pilot lights, and a 120V
control circuit transformer.

*Optional ranges available are 50 to 300°F or -20 to 120°F.

WIRING

INSTALLATION

DANGER: Hazard of Explosion or Fire. The tank

must be purged of all flammable vapors prior to
cutting or welding.

1. Select a location for this installation according to the following:
A. Heating elements are removable thru the lower half of the

control enclosure but adequate room must be provided for
this purpose. This removal length for the RST would be
equal to the length “B” dimension as tabulated in the
Specifications Table 1. The element removal length for the
RSTO is 3 foot since it can be bent on a 12” radius.

B. The control enclosure should not be located where it will be

in direct sun light or be affected by any other heating equip­ment in the area.

2. Cut a rectangular hole in the tank approximately

1

/4” larger than
the adapter box dimensions tabulated on the Specification
Table 1.

3. Install heater tube supports on 10 foot centers before installing
Immersion Heater assembly (refer to Figure 1). Do not anchor
the heater tubes to the supports as the tubes must be allowed to
expand.
Note: Heater tubes should be level or slightly inclined away
from the control panel.

4. Insert heater tubes and position adapter box as per Figure 1.

5. Weld adapter box to tank insuring that the weld is liquid tight.

6. Tank suction pipe should be mounted at least 2” above the level

of the heaters. A separate line can be provided to drain tank
after heaters have been de-energized.

CAUTION: Hazard of Electric Shock. The Unitary
Immersion Heater must be grounded using ground­ing means provided in the control box and employ­ing wiring in accordance with National Electrical
Code.

1. This heater assembly is completely prewired. The only wiring
necessary is the terminals L1, L2, L3 on the main circuit break­er and the grounding lug in the control panel.
Note: All electrical connections should be checked and tight­ened if necessary. These sometimes loosen during transit.

2. The Unitary Immersion Heaters’s internal wiring is per the typ­ical wiring diagram (Figure 2) with the kW loads being tabu­lated in Table 2.

kW/Circuit

Model A B

RST (or) RSTO-21915 7.5 7.5
RST (or) RSTO-21920 10.0 10.0
RST (or) RSTO-21925 12.5 12.5
RST (or) RSTO-51530 18.0 12.0
RST (or) RSTO-52038 22.8 15.2
RST (or) RSTO-31518 12.0 6.0
RST (or) RSTO-41524 12.0 12.6
RST (or) RSTO-61536 18.0 18.0
RST (or) RSTO-81545 22.5 22.5
RST (or) RSTO-31720 13.3 6.7
RST (or) RSTO-41726 13.0 13.0
RST (or) RSTO-51732 19.2 12.8
RST (or) RSTO-61740 20.0 20.0
RST (or) RSTO-71848 27.4 20.6
RST (or) RSTO-31922 14.7 7.3
RST (or) RSTO-41930 15.0 15.0
RST (or) RSTO-51936 21.6 14.4
RST (or) RSTO-61945 22.5 22.5
RST (or) RSTO-72156 32.0 24.0
RST (or) RSTO-32024 16.0 8.0
RST (or) RSTO-42336 18.0 18.0
RST (or) RSTO-52548 28.8 19.2
RST (or) RSTO-62660 30.0 30.0
RST (or) RSTO-72672 41.1 31.9

Figure 1 — Typical Installation in Dished Head Tank

Table 2

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