Does the flow orifice plate directly measure volume flow or mass flow?
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Does the flow orifice plate directly measure volume flow or mass flow?
The flow rate directly measured by the orifice plate depends on the unit. If it is m3/h, it is the volume flow rate. If it is kg/h, it is the mass flow rate. However, this mass flow rate is not a qualitative quantity, because it is also related to temperature, pressure, etc. That's just what we usually call it.
Those on the second floor still don’t understand! What is the direct quantity measured by the orifice plate? It should be the volume flow rate, and then indirectly calculate the mass flow rate and display it on the transmitter?
The volumetric flow rate is calculated based on the pressure difference generated by the flow rate.
What the orifice plate measures is the differential pressure before and after the orifice plate, and the volume flow rate is calculated through relevant calculations. If a density is introduced for calculation, the mass flow rate can be obtained. Since density is closely related to medium characteristics and temperature, the result error is also relatively large.
It depends on whether the user requires volume flow or mass flow. Generally, the measured medium is gas, which is the volume flow rate. ； The measured medium is liquid and steam, which is the mass flow rate. When we were in school, when calculating orifice plates, different formulas were used for media with different phases. There are two formulas for mass flow and volume flow.
The orifice plate measurement is a flow value converted by the differential pressure method. There are certain differences in the design of different orifice plates in terms of mass or volume. Generally, the process parameters provided during orifice plate design give density, viscosity, maximum, minimum, and normal flow. Liquids generally use mass flow, and gases use volume flow. Specific to each orifice plate, the parameters are different, and the corresponding uses are different, and they are not interchangeable.
is the volume flow rate. The mass flow rate is the volume flow rate times the density.
What the orifice plate measures is the pressure difference. The so-called volume flow or mass flow is converted by the secondary meter. If you need mass flow, you also need to enter the density of the medium when setting the secondary meter.
A direct mass flow meter can be formed by combining an orifice plate (or venturi tube) and a quantitative pump. A differential pressure flowmeter and a density meter are combined to calculate the mass flow rate, which is an indirect mass flow meter. The indirect mass flow meter consists of a differential pressure flow detection component and a volumetric flow meter.
The orifice plate is a primary element that provides a differential pressure for measuring flow through throttling. Whether this flow is volume or mass depends on the settings of the transmitter and has nothing to do with the orifice plate.
The orifice plate originally measured the volume flow rate, because this is a volume formula that was obtained through millions of experiments. So it is the most mature. With the volume, can you calculate the mass? Of course, except if you don't know the density of the object you are measuring.
The orifice plate is composed of a velocity flow meter. What is measured is a signal related to velocity, and then the volume flow rate is calculated based on the velocity. It is also possible to calculate the mass flow rate.
It seems that orifice plates generally have volumetric flow rates.
The orifice plate can only measure volume flow, and mass flow is converted from density.
First, the volume flow rate is directly measured, and after conversion and calculation, the mass flow rate can be displayed.
In fact, the orifice plate measures the flow rate, which of course can only be the volume flow rate. If temperature and pressure compensation are added, the mass flow rate can be measured indirectly.