Chromalox PQ410-4 service manual General, Use The Right Heat Transfer Fluid, Pipe Strain, July

SERVICE MANUAL

4	CES
(Supersedes PQ410-3)	PQ410-4

161-048978-001

JULY, 2009

Electric Fluid Heat Transfer Systems

GENERAL

This Service Manual is furnished as an aid to help start-up and service Chromalox Heat Transfer Systems. Listed below are con- ditions which could occur during start-up and operation.

CAUTION: Hazard of Electric Shock. Any installa- tion involving electricity must be grounded to earth to eliminate shock hazard.

1.USE THE RIGHT HEAT TRANSFER FLUID

DO read manufacturer’s technical bulletins and instructions care- fully. Some heat transfer fluids may ignite or burn spontaneously if not properly used.

Chromalox Fluid Heat Transfer Systems are designed for a par- ticular heat transfer fluid or a class of heat transfer fluids. If you are not sure you are using an accepted heat transfer fluid, check with your local Chromalox sales and application engineering office listed on back cover or consult Chromalox Bulletin PQ301 for the correct heat transfer fluid.

DO NOT mix heat transfer fluids unless authorized and approved by the fluid manufacturer.

All heat transfer fluids are not compatible with each other, whether made by the same manufacturer or a different manufac-

turer. If you plan to switch fluids, check with the fluid manufac- turer to determine the following.

A.Is the new fluid compatible with the old?

B.What is the recommended cleaning method to remove the old fluid, its sludge, or any deposits remaining in the system?

C.Does the fluid manufacturer have a reclaiming service for used fluid? Do they have a recommended procedure for disposal of used or old fluid?

CAUTION: To avoid possible damage to the heaters do not energize the heater unless the system is filled with fluid.

2. PIPE STRAIN

DO provide for expansion and contraction of process piping and connections to the system. Piping strains can cause pump and motor mis-alignment, excessive wear on pump body, bearings and stuffing box packing or mechanical seal and will eventually cause failure of the pump and system.

Piping should be properly supported so pump can be removed without changing the position of the piping. If piping moves when the pump is removed, pump malfunction is probably due to stress- es and twisting caused by the piping. These stresses will multiply when the system is hot due to thermal expansion.

3. PIPING RESTRICTIONS

DO provide sufficient cross sectional area in the process piping connections equivalent to the system pipes. In order to prevent undue pressure drop, maximum velocity in all piping should be less than 10 feet per second.

DO NOT use process piping connections smaller than the pipes used in the system.

If there is a high differential pressure between the inlet and out- let of the heat transfer system at operating temperature, this is probably due to a piping restriction. A continuing high differential

pressure can cause excessive wear on the pump and pump stuffing box packing or mechanical seal and will eventually cause prema- ture failure of the pump. The major causes of restrictions are:

A.Inlet and outlet pipes smaller than provided on the system.

B.Piping many processes in series with one another. To reduce the pressure drop of the system, equipment should be re-piped in balanced parallel flow.

© 2010 Chromalox, Inc.