GENERAL INFORMATION AND OPERATION:

The High Pressure Selector Relay Model 58S selects the higher of two signals and releases it directly to the next element of an instrument circuit. There is no retransmission which means there will be no time delay caused by this relay.

As shown in the schematic (Figure 1), input pressure “A” is directed to the top of the floating disc and input pressure “B” to the bottom. When input pressure “A” exceeds input pressure “B” the floating disc moves down closes the “B” input air passage, and permits the greater “A” input pressure to pass through to the output.The reverse occurs when input pressure “B”

is greater.

Model 58S is supplied with a Neoprene floating disc and is limited to maximum input pressures of 30 psi. Model 58SH is supplied with a Teflon floating disc and is limited to maximum input pressures of 100 psi. Model 58SH can be used for pressures below 30 psi but small leaks from an input, past the floating disc and to the output, may occur.
 

MATERIALS OF CONSTRUCTION:
Aluminium body, neoprene or Teflon floating disc.