Watlow Electric 316-42-5-1 User Manual

WATLOW IND. WATROD

Circulation Heater Installation & Maintenance Manual

I&M NUMBER: 316-42-5-1 Page: 1
Date: 6/11/2008 Rev: 2.00

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Pre Installation

• Check to make sure that heater received is the same as that ordered.

• Watlow heaters are built to comply with UL and CSA dielectric requirements, it may be necessary due to

atmospheric conditions / humidity, to perform a dielectric test prior to startup. (Refer to megohm test
under Installation section)

Safety

Electric heaters are inherently dangerous!! Care should be taken to read and completely understand the

Installation and Maintenance manual before installing and wiring the heater. Any installation and
maintenance performed on the heater shall be done by a qualified electrician, in accordance with the
"National Electric Code" and other electrical codes as they apply. It is the users responsibility to ensure that
the heater being used is properly selected and installed in the application.

!

The Caution Symbol (exclamation point) alerts you to a "CAUTION", a safety or

functional hazard which could affect your equipment or its performance.

The warning symbol (lightning bolt) alerts you to a "WARNING", a safety hazard which

Installation

Proper heater selection and installation will result in efficient heat transfer, safe operation, and long heater
life.

1. Megohm precheck

During shipping and/or storage, the possibility of moisture absorption by the insulation material within the
element is possible. To ensure proper megohm values a minimum 500 VDC megohm meter (Megger)
should be used to ensure that the megohm reading between the heater terminal and the heater sheath is
more than 10 megohms when the unit is at room temperature.

If several units are interconnected, the megohm of the heater is obtained by taking the reading and
dividing by the number of interconnected elements. This reading should be greater than 10 megohms.

If a low megohm value exists, two alternative methods can be used to remedy the situation. The best
method is to remove all terminal hardware including thermostat if provided, and bake out the heater at no
higher than 250°F (120°C) overnight or until an acceptable reading is reached. The second method is to
energize the unit at low voltage in air until the megohm is at an acceptable reading. Care should be
taken to prevent the heater sheath from exceeding 750°F (398°C) for Incoloy® and steel elements
and 400°F (204°C) for copper elements. Both of these methods should be performed with the heater out
of the tank. The orientation of the heater in relation to the tank should be observed in order to reposition
the heater properly. This is especially important if a high limit thermocouple is provided.

2. Protection of heater elements from over temperature
The use of temperature controls to regulate heating process and prevent heater over temperature is

highly recommended to ensure safe heater operation. It is the users responsibility to ensure safety of
the installation.

WARNING: Install high temperature control protection in systems where an over temperature
fault condition could present a fire hazard or other hazard. Failure to install temperature control
protection where a potential hazard exists could result in damage to equipment and property,
and injury to personnel.

could affect you and the equipment

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]

WATLOW IND. WATROD

Circulation Heater Installation & Maintenance Manual

I&M NUMBER: 316-42-5-1 Page: 2
Date: 6/11/2008 Rev: 2.00

________________________________________________________________________________________________________________________________________________________________________________________________________________________

Failure of components in a temperature control loop, such as the sensor, heater control relay or main

temperature control, can result in damage to a product in process, a melt down of a heater, and / or
damaging fire.

To protect against this possibility, over temperature protection must be provided to interrupt or remove

power from the heater circuit. A bulb and capillary thermostat is not recommended for this function

since it may not respond quickly enough to adequately protect the heater. In cases where the
thermostat bulb gets too hot before the system is turned off, the thermostat bulb could rupture.
This could result in the thermostat remaining in the "ON" condition since there is insufficient
fluid to move contacts apart. We recommend the temperature protection have appropriate third party

approval, and be applied in the classification for which it was tested and approved.

In order to help prevent premature failure and a potentially hazardous condition in cases where

consequences of failure may be severe, use an appropriate third party approved liquid level protection
device. The liquid level should be such that the entire heater is fully submerged with enough liquid above
the heater to adequately dissipate heat from itself as under normal operating conditions. Consult your
local authorized sales representative for specific recommendations for your application.

3. Terminal Enclosures
Terminal enclosures should be selected to be compatible with the environment in which the heater will

be located. It is the users responsibility to determine the need for correct rating of the electrical housing.
This should be based on appropriate national and local electrical codes. Failure to use a compatible
enclosure could result in heater damage and personnel danger.

Standard terminal enclosures are designed for general purpose use and are rated NEMA 1. These

enclosures should be applied where there will be no danger of spilled liquids, dampness, dirt, and
gaseous conditions. Enclosures for wet or hazardous locations are also available, but must be installed
at the factory.

Although enclosures are supplied over the terminals, units should be located in an area that will minimize

the chance of being hit by falling or moving objects. The terminals must be protected at all times from
moisture or vapor.

In hazardous locations, (as defined in NFPA 70, NEC, Article 501) explosion resistant housings must be

used.

In order to maintain termination integrity, the terminal enclosure should be kept below 400°F
(204°C).

4. Orientation / Mounting
Furnish adequate space for horizontal or vertical installation. Space should be allowed for immersion

heater removal from tank.

Approved methods for installation of air (gas) and liquid units are shown in Figures # 1 and # 2. Take

careful note of the inlet and outlet locations. Positions other than shown are not recommended.

Figure # 3 shows the preferred position of the circulation heater when pumping liquid from a tank

through the heater. The NPSH (Net Positive Suction Head) is one of the most important factors when
determining the location of the heater.

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]

WATLOW IND. WATROD

Circulation Heater Installation & Maintenance Manual

I&M NUMBER: 316-42-5-1 Page: 3
Date: 6/11/2008 Rev: 2.00

________________________________________________________________________________________________________________________________________________________________________________________________________________________

OUTLET

INLET

AIR / GAS APPLICATION

OUTLETINLET

OUTLET

INLET

LIQUID APPLICATION

OUTLET

Figure # 1 Figure # 2

NPSH

PUMP

INLET

INCORRECT HEATER POSITION - HEATER ABOVE NPSH

NPSH

PUMP

CORRECT HEATER POSITION - HEATER BELOW NPSH

Figure # 3

When installing piping connections, care should be taken to avoid supporting the tank by the nozzles.

Mounting blocks are provided to help prevent this. Provisions for thermal expansion and contraction
should be considered, slotted bolt holes in one of the mating mounting pads would do adequately.

Installation of an isolation valve and pressure relief valve is recommended but not provided. Rating of

valves should not exceed the ANSI class 150 flange rating. Two 1/2" FNPT couplings are provided for
drainage and installation of valves.

DANGER: HAZARD OF FIRE. Electric heaters are capable of developing high temperatures so extreme

care should be taken to locate heaters in safe environments. Mounting heaters in atmospheres
containing combustible gases and vapors should be avoided. According to article 501 of the NEC, the
maximum surface temperature of the heater shall not exceed 80 % of the auto-ignition of the surrounding

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]