Direct & Indirect Water-cooled Resistors

Ohmite's direct and indirect water-cooled non-inductive resistors are capable of dissipating more power in a smaller package than water-cooled resistors previously available in the market.

Type Power, Watts Dimensions,
Resistance range (nominal)
  Rated power Max. power A B C Tol. = ±10
W500SP 350 500 1.97 1.18 0.79 1-100 Ohm
W1000SP 750 1000 2.36 1.77 1.18 1-100 Ohm

Application Considerations

Water Purity

Specific life data with defined water conditions is not available. It has been observed that life expectancies of higher resistances (ex. W500SP>20 ohms), may vary from 1 to 5 years depending on the water purity.

Higher resistance values cause increased conduction in the water which deposits contaminants on the resistor I.D. These deposits reduce heat transfer, deteriorate the silicone seal and inhibit water flow, all of which can cause premature failure..

Good quality drinking water may give 1 to 2 years life where high purity water may increase life by a factor of 5.

Water Pressure

Assemblies are tested at 85 psi; however, for long-term reliability, it is recommended that the operating pressure be at 42 psi or lower.

Mechanical Considerations

The ceramic resistor is fairly rugged; however, the acrylic and polycarbonate parts with the epoxy seals require that care be taken during assembly or transport. Rapid water pressure changes should also be avoided.