The Alicat Scientific PC series is a single-valve digital pressure controller that integrates a precision pressure sensor, proportional control valve, and PID controller into one compact instrument. Unlike conventional pressure regulators that rely on mechanical springs and diaphragms, the PC uses a digital sensor and high-speed processor to measure pressure thousands of times per second and adjust the valve in as little as 30 milliseconds. The result is closed-loop pressure control from 0.01% to 100% of the device's full-scale range — a 200:1 turndown ratio — with NIST-traceable accuracy of ±0.25% of full scale.

How does the digital control architecture work?

Pressure is measured by a MEMS or piezoresistive sensor (depending on range) and compared to the user-set setpoint. The onboard PID loop — with user-adjustable gain, integral, and derivative constants — drives a fast proportional valve to add or vent gas on the process side. The standard control loop runs at approximately 50–100 ms, but can be tuned as fast as 30 ms for low-volume systems. Setpoint ramping smoothes transitions between pressure levels, preventing overshoot in sensitive downstream equipment. A backlit LCD displays pressure, setpoint, and engineering units simultaneously, while the integrated push-button interface allows field configuration without a connected computer.

What pressure ranges and valve options are available?

The PC series covers gauge pressures from a few inches of water (0–0.07 PSIG / 2 inH₂O) up to 3000 PSIG, with absolute pressure versions from 0–15 PSIA to 0–3000 PSIA and differential ranges from ±2 inH₂OD to ±100 PSID. Several valve variants adapt the controller to different flow and pressure requirements: the standard PC valve suits sub-20 SLPM applications; PCA handles higher pressures; PCH mounts two small valves side-by-side as a single unit; and PCR uses a large Rolamite valve for flows from 20 to 2500 SLPM. For corrosive gases or liquids, the PCS and PCX series offer wetted materials in stainless steel with FFKM or metal seals.