Fast Pressure Controllers & Transducers

model

PCD–Dual Valve Differential Pressure Controllers

Closed-volume differential pressure control

Measure the differential pressure between any two points in your closed process volume, and control flow at a different point to ensure the pressure differential remains constant. Alicat’s PCD series dual-valve pressure controllers use two proportional valves to precisely control the pressure of gases within dead-ended volumes. The two process ports connect to opposite sides of the differential pressure sensor; positive readings denote higher pressure at the left (upstream) process port, and negative readings denote higher pressure at the right (downstream) port. We’ll use your application parameters to customize your valve and PID tuning to ensure that your controller delivers fast and stable control.

  • Fast & Accurate. Very fast valves and PID control algorithms hit pressure setpoints in milliseconds with NIST-traceable accuracy.
  • Connected. Easy integration into your digital industrial network with Ethernet/IP, EtherCAT, DeviceNet, Profibus, Modbus (RTU and TCP/IP) or serial communications options.
  • Efficient & Versatile. The dual-valve design incorporates a second proportional valve to exhaust excess pressure, but only when needed to maintain your setpoint. Plumb the two pressure ports wherever you need to measure and control the pressure difference. Or use the instrument as a gauge pressure controller by leaving the downstream port open to atmosphere.

Available Ranges (see Part Numbers tab for stock ranges)

  • PCD: max -100 to +100 psid, min -2 inH2Od to +2 inH2Od
  • PCDS: max -100 to +100 psid, min -5 to +5 psid

Performance

  • Turndown ratio: 200:1
  • Standard accuracy calibration, NIST-traceable: +/- 0.25% of the full-scale range
  • Optional high-accuracy calibration, NIST-traceable: +/- 0.125% of the full-scale range
  • Repeatability: 0.08% of the full-scale range
  • Typical control response time constant: 50-100 ms (as low as 25 ms with PID tuning, dependent upon line sizing and the volumes and pressures involved)
  • No warm-up time required

Operating Conditions

  • Compatible gas media: all non-corrosive gases (PC/PCS). Liquids and corrosive gases require an S-series device (PCS).
  • Operating temperature: -10°C to +60°C
  • Burst pressure: 3x the full-scale range
  • Common Mode Pressure: 150 psig

In the Box

Model Variations 

  • Aggressive gases (PCDS, see below)

Also available:

  • Single valve configuration for flowing processes (PC)

Valve Options 

Your pressure controller may be customized with one of the following valving options to ensure optimal performance under your expected process conditions.

  • PCD – small proportional control valves for flow ranges of 20 slpm and below
  • PCD with PCA designation – high-performance proportional control valves used for applications with higher pressures
  • PCDP – small proportional control valves with the largest orifice (not available for corrosive configurations)
  • PCDH – hammerhead configuration, which pairs two small valves working side-by-side as one valve at each of the two valve positions
  • PCRD – nearly frictionless large Rolamite proportional valves for flow rates of 50 slpm and above

Liquids and Corrosive Gases (PCDS series)

Instruments in the standard PCD series are also available with an optional “S” configuration (PCDS) for use with liquids and corrosive gases. In this configuration, we upgrade the valves to 303 stainless steel, the sensor to 316L stainless steel and the elastomers to FFKM. Some corrosive gases require 316L stainless steel throughout the flow path, and in this case we can upgrade both the valves (type PCA) and flow body to 316L for full-scale flow ranges of 20 slpm or less.

Build Options

  • Communications protocols (analog, RS-232, RS-485, DeviceNet, EtherCAT, Ethernet/IP, Modbus RTU or TCP/IP, PROFIBUS)
  • Displays (monochrome or color, integrated or panel-mount)
  • Process connections (NPT, SAE, AN, BSPP/G, welded compression or VCR/VCO fittings)
  • Elastomers (Viton, FFKM, EPDM, Silicone)

Performance Options

Alicat’s PCD series uses small proportional valves for control at lower flow rates and is suitable for use with non-corrosive gases.

Differential Pressure:

PCD-2INH2OD-D
PCDAS-1PSID-D
PCD-1PSID-D
PCD-5PSID-D
PCD-15PSID-D
PCD-30PSID-D
PCD-100PSID-D

Alicat’s PCDP series offers the largest orifice in a small valve format and is suitable for use with non-corrosive gases.

Differential Pressure:

PCDP-2INH2OD-D
PCDPAS-1PSID-D
PCDP-1PSID-D
PCDP-5PSID-D
PCDP-15PSID-D
PCDP-30PSID-D
PCDP-100PSID-D

Alicat’s PCDH series pairs two small valves working side-by-side as one and is suitable for use with non-corrosive gases.

Differential Pressure:

PCDH-2INH2OD-D
PCDHAS-1PSID-D
PCDH-1PSID-D
PCDH-5PSID-D
PCDH-15PSID-D
PCDH-30PSID-D
PCDH-100PSID-D

Alicat’s PCRD series uses nearly frictionless Rolamite valves and a variety of orifice patterns for control at high flow rates and is suitable for use with non-corrosive gases.

Differential Pressure:

PCRD-2INH2OD-D
PCRDAS-1PSID-D
PCRD-1PSID-D
PCRD-5PSID-D
PCRD-15PSID-D
PCRD-30PSID-D
PCRD-100PSID-D

Alicat’s PCDS series uses small proportional valves for control at lower flow rates and is suitable for use with liquids and corrosive gases.

Differential Pressure:

PCDS-5PSID-D
PCDS-30PSID-D
PCDS-100PSID-D

Alicat’s PCDHS series is suitable for use with liquids and corrosive gases and pairs two valves working side-by-side as one to provide greater control at higher pressures.

Differential Pressure:

PCDHS-5PSID-D
PCDHS-30PSID-D
PCDHS-100PSID-D

Alicat’s PCRDS series is suitable for use with liquids and corrosive gases and uses nearly frictionless Rolamite valves and a variety of orifice patterns for control at high flow rates.

Differential Pressure:

PCRDS-5PSID-D
PCRDS-30PSID-D
PCRDS-100PSID-D

Valve Characterization in Martian Environments

To characterize a valve’s flow vs pressure curve as it would be used on Mars, Alicat’s dual-valve differential pressure controller can cycle through several pressure differentials that are all referenced to the simulated Martian atmosphere instead of Earth’s own atmospheric pressure. Plumb the downstream differential pressure port to the closed atmospheric chamber and the upstream one to the line that supplies pressure against the valve.

 

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