• Pneumatic Indicator

Pneumatic Indicator

For Piezometer

  • DGSI - Slope Indicator 256

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The 256 pneumatic indicator is used to read pneumatic piezometers and settlement cells.

It features a precision flowmeter, a return-flow indicator, convenient controls, a large internal tank, and an analog or digital pressure gauge.

Before leaving for the site, check that the indicator’s tank is charged with gas. The built-in tank holds more than 180 liters of gas (6.25 SCF), which is sufficient for busy reading schedules. On site, set the pressure regulator. Proper regulation results in lower gas consumption and prevents damage to the pressure gauge. Connect transducer tubing to the indicator using the included jumper tubing.

Turn on the gas to activate the transducer. Gas flows down through the tubing to the transducer. Wait for the return-flow indicator to show a return flow of gas, then shut off the gas or use the precision flowrate valve and flowmeter to slow the flow of gas. Wait for the pressure reading on the main gauge to stabilize, then write down the reading. Take a second reading for verification, then disconnect and move to the next transducer.


  • Choice of Pressure Gauges
    Both digital and analog gauges are available.
  • Precision Flowmeter
    Use the precision flowmeter when reading with flow or when pressuring long lines.
  • High Quality Components
    The 256 Indicator is built for hard and long use. It employs the best quality tube fittings, tubing, valves, gauges, and tank.

Twin Tube Indicator Includes

  • Pressure gauge
  • Precision flowmeter
  • Filler hose
  • Twin-tube jumper
  • Manual.

Please specify range and units for pressure gauge. Indicators shipped by air have empty tank.


CAT. NO. Description
SI51425601 With 0.25% Analog Gauge
SI51425602 With 0.05% Digital Gauge
Pressure Gauge 0.25% analog gauge or 0.05% digital gauge. Digital gauge uses a 9 volt battery.
Working Range Determined by range of pressure gauge and by pressure regulator. Standard regulator outputs a maximum pressure of 1.24 MPa (180 psi).
Internal Tank 1.38 liter (84 in3). Typical capacity is 180 liter (6.25 SCFH). Working pressure is 13.9 MPa (2015 psi). Recommended gas: dry nitrogen, 3 ppm H20 maximum.
Precision Flowmeter The flowmeter provides a repeatability of ±0.5% FS and is pressure rated for 1.7 MPa (250 psi). It is graduated in millimeters. When reading with flow, the recommended setting is a flowrate of 30 mm, which is equivalent to 0.1 SCFH or 47 cc/min.
Filler Hose For filling tank from external nitrogen bottle. 2 m hose (7') with quick-connect fitting for indicator and screw-on fitting for external bottle.
Jumper Tubing Connects indicator to terminal panel or to transducer tubing. 2 m jumper (7') with quick-connect fittings at each end. Twintube or triple-tube jumper is supplied, depending which options are ordered.
Weight About 11 kg (24 lb) including full tank and jumper hose. Exact weight depends on selected options and pressure gauge.
Size 508 x 457 x 178 mm (20 x 18 x 7")