In Part VII of our natural gas flow meter types’ series, here I discuss the orifice plate, a differential pressure meter commonly used to measure natural gas flow when high accuracy is not required.

Differential Pressure Natural Gas Flow Meter

Differential pressure (DP) flowmeters determine flow by measuring pressure drop over an obstacle inserted in the flow pathway. Common types of these flow devices are orifice plates, averaging pitot tube, venturi tubes and flow nozzles.

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Natural Gas Flow Meter Types | Orifice Plate Differential Pressure
The orifice plate is a natural gas flow meter type that determines flow by measuring pressure drop over an obstacle inserted in the flow pathway.

Orifice Plates

The orifice plate (orifice meter) is a differential pressure meter frequently used in natural gas measurement. It measures volumetric flow, though can also calculate mass flow depending on the calculation associated with the device. It uses the same principle as used in a Venturi-style meter (Bernoulli’s principle), suggesting that there is a relationship between the velocity and pressure of the fluid. That relationship is – as the velocity increases the pressure decreases. With an orifice meter, the flow is determined through the difference in pressure between the upstream and the downstream side of a partly impeded pipe.

Advantages

Orifice plates have a long history of use; there is wide industry acceptance, and they are well documented in standards. They are simple and inexpensive. The orifice meter has no moving parts and is mechanically stable. Dry calibration is acceptable, and there are no limits on temperature, pressure or size.

Limitations

On the down side, orifice meters have low accuracy at low flow conditions. They have low turndown/rangeability and a high-pressure loss which can impact operating cost. Additionally, orifice plates are flow-profile sensitive and require a long meter tube or flow conditioner; they are not self-cleaning and can be damaged or clogged by high flow rates. Also, to calculate mass flow temperature and pressure correction is required.

Orifice Plate Manufacturers

There are many differential pressure orifice plate manufacturers, too many to list in this post.

If you are interested in natural gas flow measurement, you may want to review other meter styles, including ultrasonic meters, diaphragm meters, rotary meter, turbine, Coriolis, and of course the thermal mass flow meters.

2 thoughts on “Orifice Plate | Part VII Natural Gas Flow Meter Types

  1. Avatar
    Edward Lewis says:

    I have been researching the Dale-hoodville consolided field (reifinery) for about 3 months. Mostly
    because I just enjoy history , and mostly (in the begining ) for my own interest in how refineries
    work. I found finding information on the refinery in Dale Ill. was extreamly difficult .I did find most
    of the information I was looking for , but I haven’t been able to find a picture of the gas meter tied
    to each well site . 250-300 well sites, It was a cast iron case with with a paper disk to obtain the
    information , with a red and black hand non-elect. with a wind up good for 1 week it was mounted
    on a loop 45 out of ground 10′ across and 45 back down, with two flanges in center w/orifice in center
    I have a picture of this, w/a gate valve on each end for servicing , without this meter the refinery would
    have never existed. (no elect. in the oil fields in 1940) . Could you please give me a clue as to how I
    could come up with a picture of this meter , used form 1942 to 1965. when the refinery closed down.
    Texas oil co. installed it (name changed to Texico inc. in 1959.

  2. Avatar
    Edward Lewis says:

    I have 16 8×10 pictures of the refinery, one from an airplane showing most of the refinery. Extremely
    good pictures, and one of the loop the meter is mounted on. when I started I thought pictures would
    be the most difficult part to find, some how someone forgot to remove the loop I have a picture of. I
    was suprised to see the chemicals that could be extracted from natural gas, including 2-3 types of
    butain plus several more including gasoline . This also prevented all of this gas from being burnt off.
    I was suprised to find so few natural gas refineries in the US . from 1900 to present.

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