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The Dwyer Series 475 Mark III intrinsically-safe digital manometer provides positive, negative, and differential pressure measurements, and is used to perform field calibration, monitoring or troubleshooting HVAC systems, performing clean room inspections, air velocity monitoring, and natural gas appliance-line testing. The meter is FM-approved intrinsically safe for Class 1, Div. 1, Group A, B, C, D, T4 hazardous locations. It has an accuracy of + or - 0.5% of full scale at 60 to 78 degrees F, and + or - 1.5% full scale at 32 to 60 and 78 to 104 degrees F. The extruded aluminum case provides durability. The backlit four-digit LCD displays the pressure measurement. The zero function nulls minor pressure differences before measuring. Standard connections accept 1/8" or 3/16" inside diameter (ID) vinyl or rubber tubing. The meter is powered by a 9V battery (included) and automatically shuts off after 20 minutes to preserve battery life.
SpecificationsPressure typesPositive, negative, and differentialMedia typeAir and compatible combustible gasesCase materialExtruded aluminumDisplayFour-digit LCDTemperature limits0 to 140 degrees F/-17.8 to +60 degrees CCompensated temperature limits32 to 104 degrees F/0 to 40 degrees CDimensions6-17/32 x 2-13/16 x 29/32 (H x W x D)Power9V alkaline batteryAgency approvalsCE, FMH 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.
Steve S.
2025-08-16 18:48:50
Quality quality quality
Vanny
2025-08-09 11:43:30
The goods arrived same as the desription. It's arrived earlier than the estimated time. Has been tested and looks working good.
lm 808
2025-08-05 17:13:47
Have a lot of hospital construction projects and need manometers to monitor our neg air containment. We had a bunch of Extech manometers but we were getting readings that didn't make sense. Picked up these Dwyer units and they work fantastic. Since we need readings down around only .02" wc, the very low range of these are perfect. Buying more of these as they become available.
kevin mckenna
2025-06-27 14:59:22
Nothing wrong with product, buynow brands suck for changing $26 for a return fee… never buying from them again!
Larry Shultz
2025-06-05 14:58:32
I have only used this once. I checked gas pressure on a furnace installation. I was easy to use and made checking and adjusting easy. It is well built and has an easy to read LCD screen. For the price, quite a bargain.
Robert Sanges
2025-05-28 10:44:37
I have 3 ranges of the 475 Mark III. Two of them were defective right out of the box. Both problems were related to poor alignment of the pushbuttons with the underlying switches. It's not that they were damaged in shipping - they were built broken.When they work they are fine - simple, but fine. It's difficult to find anyone other than Dwyer who makes a digital manometer that is listed for combustible gas service. Dwyer needs to give their quality control department a kick in the pants.
B2B Industrial
2025-05-05 14:13:46
Arrived promptly and works well. However it could a case to keep it from damage in a tool case and some tubing even if it was a small amount so it could be used immediately.
Bill
2025-03-28 12:47:32
Needed this for my business in air purification. Great price, fast shipping, and the model I wanted. Would recommend this to anyone needing a quality manometer. Last one worked great for 15 years and would still be going strong if I could have found a bottom replacement cap.
Andrew
2025-03-11 12:04:31
Item is as explained. Quick delivery
Customer
2025-03-06 17:04:55
great product
Customer
2025-01-28 12:04:07
came without tubing to attach frustrating having to go buy 1 foot of tube before you can use it. other than that worked fine.
Bill Graefer
2025-01-09 10:01:02
Great deal
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