The Dwyer 1211 series slack-tube roll-up manometer measures static, vacuum, and differential pressure of air and gas in fan and blower tests, gas pressure evaluation, and calibration applications. The manometer has an acrylic plastic top, connectors, and over-pressure traps for use with testing air and gas, and vinyl tubing for use with mercury (sold separately) or water with fluorescein green concentrate (sold separately). The manometer is calibrated in inches of water using water and is suitable for use with mercury or water with fluorescein green concentrate measuring fluids (sold separately). The connectors accept 1/8" tubing and can be turned to seal the fluids during storage or transport. The flexible spring-steel scale is mounted between the columns to eliminate parallax reading errors, and the 2" sliding zero adjustment provides zeroing capability. The manometer has a maximum intermittent total pressure of 50psi and vacuum up to 20 inHg. The manometer can be hung or mounted using the attached magnets.

H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.

Manometers measure the pressure of a liquid or gas. They are used in laboratory, medical equipment, engineering, automotive, and heating, ventilation, and air-conditioning applications. Manometers measure any combination of gauge, absolute, or differential pressures. Gauge pressure is the amount of pressure in a system relative to the ambient pressure, absolute pressure is the amount of pressure in a system relative to an absolute vacuum, and differential pressure is the difference between two pressures. Analog manometers are composed of columns of liquid, and they use gravity and the liquid's density to calculate pressure. Because they have no moving parts, analog manometers do not require re-calibration. Digital manometers have pressure sensors that are connected to a system with a hose to provide a digital readout of the amount of pressure present in a system. They use microprocessors to calculate pressure, and they require periodic calibration to help ensure accuracy.

Dwyer Instruments manufactures measurement and control instruments, including pressure gauges, flow meters, level instrumentation, temperature instrumentation, and air quality monitors. The company, founded in 1931, is headquartered in Michigan City, IN.