The EM700 uses an inclined column of red indicating oil to magnify low differential-pressure changes. Its mechanical measurement requires no electrical power or batteries. Typical applications include HVAC filter monitoring, cleanroom pressure indication, ventilation ducts, fan and blower checks, furnace draft and air-velocity measurement with a Pitot tube.
A precision-molded ABS body and ultrasonic welded sealing form the housing. The low-volatility red oil gives a visible reading, while a built-in overflow reservoir helps retain the fluid during pressure excursions. A spirit level and external zero-adjustment knob simplify setup.
| Parameter | Specification |
|---|---|
| Scale | -10 to 0 to 700Pa |
| Accuracy | ±3% at 21°C |
| Measuring medium | Air and compatible noncorrosive gases |
| Operating temperature | -10°C to 60°C |
| Maximum internal pressure | 10psi, approximately 68.9kPa or 0.689bar |
| Indicating liquid | Red gauge oil, specific gravity 0.826 |
| Mounting | Vertical surface; align using the built-in spirit level |
| Pressure ports | Left HIGH; right LOW |
| Tubing set | 2.4m flexible twin tubing with 1/8in NPT adapters |
| Fluid bottle | 35mL |
| Other accessories | Two mounting screws, tubing/duct adapters, indicator flags and instructions |
The internal-pressure limit is separate from the differential measuring scale. The overflow reservoir does not extend the maximum pressure rating.
Mount the gauge on a flat vertical surface using two holes approximately 3.6mm in diameter, spaced 100mm vertically. Leave the screws loose until the spirit-level bubble is centered, then tighten and recheck alignment. Keep the instrument away from chlorinated vapors and solvents such as benzene, acetone and carbon tetrachloride.
Turn the zero knob counterclockwise to its stop, then clockwise about three turns to place it near the middle of its adjustment range. Remove the fill plug and slowly add the specified red oil until the level approaches zero. With both ports open to atmosphere, use the knob to align the liquid exactly with the zero mark and replace the plug. If overfilled, absorb excess oil through the fill opening with a pipe cleaner.
Mount the manometer within approximately 0.91m of the filter bank. Connect the upstream high-pressure side to HIGH and the downstream low-pressure side to LOW. The red-striped tube identifies the high-pressure connection. Position the marker flags beside the column to identify the chosen filter-condition limits.
Use a suitable Pitot tube with its tip facing into the airflow. Connect total pressure to HIGH and static pressure to LOW. A smooth, straight duct with at least four duct diameters upstream and downstream supports the described measurement arrangement. The English manual includes the velocity-pressure and air-density equations, their units and the stated limits of the centerline-to-average velocity approximation.
Check the oil level and zero periodically. Vent both ports before zero adjustment, and top up only with red gauge oil of specific gravity 0.826 when the liquid falls outside the adjustment range. Clean the housing with mild soap and water. The English manual provides complete filling, installation, connection and maintenance instructions.
