PP Series Pressure Pilots for HD Regulators

Pilot-operated regulators maintain constant downstream pressure even when the inlet pressure to the valve fluctuates or steam usage varies. The PP-Pressure Pilot is adequate for controlling pressure in most industrial applications. For increased accuracy use the PP5 Pilot.

  • The PP-Pilot can maintain downstream pressure to ±1 PSIG
  • PP5-Pilot can maintain downstream pressure to ±0.5 PSIG
  • Choices of three overlapping pressure ranges
  • Pilot is easily installed on pilot adapter using four bolts, no tubing connections are required
  • Full port strainer and blowdown valve on pilot adapter for protection of pilot from dirt and scale
  • Solid floating diaphragm is more failure resistant
  • Watson McDaniel’s pilots can be used with other manufacturers’ regulators

Catalog Specification Sheet


I&M – Quick Install

ModelPSIG AccuracyReduced Pressure RangeSpring ColorWeight (lbs)
PP-YStandard3 - 25Yellow10
PP-BStandard20 - 100Blue10
PP-RStandard80 - 200Red10
PP5-YHigh Accuracy1 - 10Yellow25
PP5-BHigh Accuracy10 - 25Blue25


The PP Series Pressure Pilots for HD Regulators are used with the HD Regulator to control steam pressure in steam mains or for process equipment.

PP-Pressure Pilot (Standard) 1.0 PSIG accuracy
PP5-Pressure Pilot (Special Applications) 0.5 PSIG accuracy

How PP Series Pressure Pilots for HD Regulators work:

  1. The Pressure Pilot controls the operation of the HD Regulator.
  2. The sensing line connects the pressure pilot to the  downstream side of the regulator.
  3. Pressure in the sensing line applies an upward force to the pilot diaphragm. This compresses the adjustment spring.
  4. When system pressure equals set point, the diaphragm moves upwards against the force of the adjusting spring. This closes the pilot valve.
  5. When the pilot valve is shut, steam cannot pass thru to the underside of the regulator diaphragm, closing the regulator.
  6. When the steam pressure falls below its set point, the pilot valve opens allowing steam to lift the main valve diaphragm which opens up the regulating valve.