LJ Engineering

L. J. Engineering manufacturers digital vacuum gauges and digital pressure gauges designed to function as stand-alone instruments for measuring vacuum and pressure of dry gases. OEM (Original Equipment Manufacturer) versions of the gages are also available for easy integration into OEM product designs. Optional liquid/air separator filters are available for systems containing liquids. Various pressure and vacuum ranges, as well as different units of measure are available. Pressure ranges and display resolution is shown in the table below. All units have an accuracy of +/-0.25% of the full scale display reading. A calibration certificate showing actual test values can be furnished for a nominal charge.

The Digital Vacuum Gauge and Digital Pressure Gauge are enclosed in a high-impact, splash-resistant ABS plastic case with mounting flanges to permit attachment to a flat surface. A 120 VAC wall transformer is included. All gauges feature 0.56-inch red LED numbers to provide optimum readability. A variety of OEM models are available to permit easy integration of the gauge display assembly into a user's control panel. The OEM models require the user to provide a DC power source of 8 to 15 volts at 250ma (minimum supply current).

Vacuum can be measured either as differential vacuum or absolute pressure. A Differential Vacuum Gauge or vacuum gauge measures vacuum relative to the surrounding atmospheric pressure. Therefore, a zero reading occurs when no vacuum is applied to the gauge. Absolute pressure references perfect vacuum as zero reading. When no vacuum is applied the gauge will indicate atmospheric pressure. As vacuum is applied the reading will decrease until perfect vacuum (zero absolute pressure) is reached, which will indicate zero. Therefore, an absolute pressure gauge at sea level will indicate approximately 29.92 inches of mercury, or 14.7 pounds per square inch, or 760 mm of mercury.

Differential Pressure Gauges measure between two different pressure sources. For example it could be the pressure difference across a filter, valve or restrictor. Differential pressure gauges require that the proper pressure relationship is applied to the corresponding port. In other words the high-pressure port must always be at a pressure equal to or greater than the pressure applied to the low-pressure port.

Please contact the factory for other pressure/vacuum ranges and units of measure or special options such as an analog output.

Product Selector

Digital Vacuum Gauges and Digital Pressure Gauges

Standard Model

OEM Model


Vacuum Measuring Scale

Please select a conversion method Conversions
Calculations are approximate. Please verify all conersions.

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