LJ Engineering

Model 484 Electronic Vacuum Regulator

The Model 484 Electronic Vacuum Regulator is designed to accept a user's analog control signal generated from its electronic system or potentiometer to adjust the set point of the vacuum regulator. Jumper settings on the regulator board allow the user to select the control signal type: external potentiometer, on-board potentiometer or external analog signal up to 10 volts. Two ranges of pressure sensors are available 484-001 (0 to 41 inches of water) or 484-002 (0 to 29.9 inches of Hg). Both models are differential pressure referenced. An absolute pressure reference sensing version is available. Three different flow range versions are available for either model regulator. The smallest flow range valve that meets the application's flow requirements should be selected in order to provide maximum sensitivity. These regulators are also capable of regulating positive pressure up to the same range as specified in vacuum. Depending on the particular installation it may be necessary to allow a small amount of bleed air into the regulated portion of the system to provide a means for vacuum to be bled off when changing from a setting of more vacuum to less vacuum.



Operating principle:

The regulator precisely throttles a proportional valve as required to maintain the desired set vacuum or pressure. The set vacuum or pressure is controlled in proportion to an analog voltage or potentiometer setting. Extremely high resoultion vacuum and pressure settings are possible. For example: Air pressure can be adjusted to the equivalent of 1-foot of altitude over a 40,000 foot altitude range.

Adjustability range, vacuum or pressure:

484-001 scalable from 0 to 41 inches of water (3 inches Hg)

484-002 scalable from 0 to 29.9 inches of Hg (15 psi)

Power Supply :

15 to 26 volts DC, 250 mA maximum current

Control Signal :

Jumper selectable by customer for any of the following:

  • External 0 to 10 volts (scalable to 5 volts or less)
  • On board potentiometer
  • Customer supplied 5k or 10k ohm potentiometer


4.70 inches by 2.25 inches by 1.74 inches high


0.27 pounds (121g)

Port Connections:

1/8 inch inside hose diameter (Tygon R polyurethane recommended)


Differential Pressure Reference

The use of a differential pressure reference will allow an application to sense pressure relative to the ambient atmospheric pressure or another pressure of interest. Differential pressure sensing will eliminate the small pressure variation which can otherwise result when atmospheric pressure changes. Differential pressure reference is the most common type of regulation reference and sensing utilized. The model 484's precision control is ideal for precision vacuum and pressure control instrumentation, ink meniscus control, vacuum clamping control and countless other applications.


Absolute Pressure Reference

An absolute pressure reference will sense vacuum compared to near zero pressure or a perfect vacuum. This operation is similar to that of the Model 329 which also references absolute pressure. Absolute pressure reference is typically used in applications such as calibration, altitude simulation, and a variety of low absolute pressure regulation situations.


Part Number : 484-XXX-Y

-XXX (range)
 -Y (flow capacity)
  -001 (0 to 3 inches Hg.)
 -1 (2.5 SCFH open flow) 0.010 inch diameter passage
   -002 (0 to 29.9 inches Hg.)
 -4 (12 SCFH open flow) 0.040 inch diameter passage
 -6 (25 SCFH open flow) 0.065 inch diameter passage

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