Dimensions

The dimensions of a standard radiator are as shown in the drawing. The variable dimensions are

• Centre distance 'CC'
• Total length 'L' depending on the number of sections
• Header pipe extension 'a'

These dimensions are to be determined by the transformer manufacturer based on the design. Generally, centre distance 'CC' increases in steps of 100 mm from a minimum of 300 mm to a maximum of 500 mm. Radiators in higher lengths can also be manufactured for specific requirements.

Cooling Sections

The cooling sections are made from 1.25 mm thick CRCA steel strips of drawing quality, in widths of 226 mm, 300 mm and 520 mm. Each radiator is made-up of a number of sections spaced at 50 mm centres, the number to be determined by the transformer manufacturer depending upon the heat to be dissipated and the maximum allowable oil excess temperature. The radiators are generally made with number of sections varying form 3 to 24. Radiators with higher number of sections can also be manufactured against specific requirements. Tables detailing the heat transmission data, the surface area, oil content and weight per section for different lengths, will be furnished on request.

Header Pipes

The top and bottom headers are each of 90 mm OD and 2 mm thickness. The headers extend 25 mm beyond the centre line of the end section and are blanked at the outer end with welded end covers.

Header Pipe Extension

An extra length of MS pipe of same OD is welded onto the headers at the open end. The length of the extension 'a' is generally 75 mm, or as specified by the customer.

Airvent Plug & Drain Plug

The detachable radiators are also provided with one airvent plug on the top header and one drain plug on the bottom header, both of RP ½ size. The airvent plug is located between the first and second sections on the open end, while the drain plug is located between the last two sections on the blanked end.

Flanges

The detachable radiators are provided with standard square flanges, 150 mm square, having 4 holes of 20 mm dia on a PCD of 160 mm, in the following thickness.12 mm for CC upto and including 1500 mm, and number of sections upto and including 24.18 mm for CC above 1500 mm, and number of sections exceeding 24.

Bracing Strapes

As a standard practice, one pair of bracing straps is provided on radiators having 'CC'1000 mm to 2000 mm, 2 pairs for 'CC' 2100 mm to 2800 mm, and 3 pairs for 'CC' above 2800 mm, Radiators with 'CC' less than 1000 mm are generally not provided with the bracing straps. The straps are made from 8 mm dia MS bright rods.

Testing

Routine pressure testing (under water) at 2.kg/cm2 for 30 minutes is carried-out for all radiators. Type tests like hot -oil sweat' and 'vacuum' withstand tests are carried out periodically, or against specific requests by the customer.

Painting

The standard radiators are blast-cleaned and given two coat each of Red Oxide Zinc Chrome primer and Enamel finish paint (providing for a total dry film thickness of 70 to 100 micro-meters) on the outside, and one coat of heat-resistant varnish on the inside. Other external primer/finish coatings such as yellow zinc chromate primer, zinc rich primer, micaceous iron oxide primer, epoxy primer/finish, polyurethane finish, spray galvanised etc, can be provided, as required.