First, orifice flowmeter overview
Differential pressure flowmeter, is a test pieces (throttle) and the secondary device (differential pressure transmitter and flow display device), widely used in gas, steam and liquid flow measurement. With a simple structure, easy maintenance, stable performance, the use of reliable and so on.
Orifice throttling device is the standard throttle parts can be calibrated directly in accordance with national standards of production, 1. National standard GB2624-81 <flow measurement throttle device design and installation and use; 2. International standard ISO5167 <International Standards Organization of the Throttle device; 3. Ministry of Chemical Industry Standard GJ516-87-HK06.
Second, the orifice flowmeter working principle
Pipes filled with pipelines flow through the throat of the throat device in the vicinity of the throttle caused by local contraction, flow rate increases, on both sides of the downstream static pressure difference.
Under the condition that the relevant parameters are known, the flow between the differential pressure and the flow can be derived according to the principle of flow continuity and Bernoulli equation. The basic formula is as follows:
C-outflow coefficient is dimensionless
D - Throttle or throat diameter of the throttle under operating conditions
D-working conditions under the upstream pipe diameter
Qm - mass flow rate Kg / s
Qv-volume flow m? / S
- diameter ratio d / D dimensionless
The density of the fluid Kg / m?
The expansibility coefficient is dimensionless
Third, orifice flowmeter structure
1, throttle: standard orifice, standard nozzle, long diameter nozzle, 1/4 round plate, double orifice, eccentric orifice, round hole plate, tapered inlet orifice, etc.
2, pressure device: ring room, take pressure flange, clamping ring, pressure tube and so on
3, connecting flange (national standards, various standards and other design sector flange), fasteners.
4, measuring tube