V-cone Flow Sensor

Principle:

In the airtight pipeline, when the medium approaches the v-cone, the pressure is P1, when the medium is passing the throttling area, the pressure would reduce to P2. Refer to Figure 1, P1 and P2 will be transmitted to the differential pressure transmitter through the two pressure tapping. The differential pressure value will change accompany with the flow velocity changing. For the stable fluid, the flow rate is in proportion to the differential pressure’s square root. If the flow velocity does not change, the larger the throttling area is, the larger the produced differential pressure value is.

Product features:

1) Rectifying of Flow state

If the fluid is flowing in a long pipeline and there is no barrier and interference, the fluid will fully developed flow. The flow velocity is not same at the different places in the pipeline, the flow velocity of the fluid near to the pipeline’s inner wall is lower, the flow velocity of the fluid at the center of the pipeline is larger, because the friction between the pipeline’ inner wall and the fluid reduces the flow velocity. If the V-cone is placed at the center of the pipeline, it will interact with the fluid at zone of high flow velocity, V-cone forces the fluid at center of pipeline mix with the fluid near to the pipeline’ s inner wall (see Figure 2), this is v-cone’s outstanding advantage, even if the flow rate is low, the V-cone flow sensor still produces differential pressure signal.

2) Accuracy

The accuracy of V-cone flow sensor can reach  ±0.5%. The accuracy of flow measuring system depends on the V-cone flow sensor’s accuracy, the differential pressure transmitter’s accuracy and the secondary meter’s accuracy.

3) Good repeatability

Repeatability of V-cone flow sensor can reach  ±0.1%.

4) Wide range ratio

The turndown of V-cone flow sensor is 10:1. V-cone flow sensor can measure the flow rate of the fluid with a lower Reynolds number.

6) Long-term stability

The shape of V-cone is a contracting body, which guide the fluid to leave away the conical surface, avoid the fluid frontal crashing to the conical surface, so the V-cone flow sensor has long term stability.

7) Signal stability

After the fluid passes the V-cone, it produces small swirls, which will be transferred into the signal of low amplitude and high frequency, this signal’s fluctuation is small, only about 1/10 of orifice plate flow sensor.

8) Permanent low pressure loss

Because there is no fluid frontal crashing on the V-cone surface, so the permanent pressure loss of V-cone flow sensor is far lower than that of orifice plate flow sensor. The pressure loss of the V-cone flow sensor is about 1/3 to 1/5 of the orifice plate flow sensor.

9) Range of V-cone’s β coefficient is wide

V-cone’s geometrical shape makes it has wide range of β coefficient, standard β coefficient: 0.45, 0.55, 0.65, 0.75, 0.85

10) The particles and dregs does not easily deposits on the V-cone.

So the V-cone flow sensor is suitable for flow rate measurement of dirty fluids.

Technical parameters:

 Installation and using:

(1) Measuring liquid flow

(a) Differential pressure transmitter should better be installed below the V-cone (see figure 1-1), thus it can prevent the gas in the fluid entering pressure tapping and the differential pressure transmitter.

(b) If the differential pressure transmitter has to be installed above the V-cone (see figure 1-2), in order to restrain the gas in the fluid from entering the pressure tapping, the “U” shape pipe shall be installed between the V-cone and the pressure tapping, and the length of the “U” pipe’s length below the pipeline’s center shall be not less than 1m.

(c) On the horizontal or slant pipeline, if install the pressure tapping at the upward side, the gas will gather in the pressure tapping; If install the pressure tapping at the downward side, the solid particles will be easy to deposit in the pressure tapping. Hence, the pressure tapping should be installed at the direction which is horizontal with the center line of the v-cone or at the position which is in angle range 0 ~ 45°from the V-cone’s center line downwards.

(2) Measuring steam flow

(a) In order to prevent the DP transmitter from the steam’s high temperature affecting, the two condensate pots should be installed at the same height between the differential pressure transmitter and the V-cone. The pressure tapping, condensate pots and the High / Low side chamber of DP transmitter shall be fully filled with condensate water to avoid the high temperature’s affect to the transmitter.

(b) It’s better to install the DP transmitter at the downward side of the V-cone (see figure 2-1), thus, can prevent gas from entering the pressure tapping. The condensate pots’ installation position shall be close to the V-cone.

(c) If the DP transmitter has to be installed at the upward side of the V-cone (see figure 2-2), the condensate pots shall be installed at the position which is higher than the DP transmitter.

(d) The blow off valve is installed close to the DP transmitter in the two installation methods above, for blow washing pressure tapping. The pressure tapping between the the V-cone and the condensate pots shall be equipped with thermal insulation layer.

(3) Measuring gas flow

(a) It’s better to install the DP transmitter at the upward side of the V-cone (see figure 3-1), thus, the produced condensate liquid in the pressure tapping can flow back to the pipeline.

(b) If the DP transmitter has to be installed at the downward side of the V-cone (see figure 3-2), in order to reduce the condensate liquid gathering in the pressure tapping, the “U” shape pipe shall be installed on the pressure tapping’s outlet, and the length of the “U” pipe’s length above the pipeline shall be not less than 1m.

(c) On the horizontal or slant pipeline, in order to prevent the condensate liquid entering the pressure tapping, the pressure tapping shall be at the upward side of the V-cone’s center line.

(d) If the gas include the dirt and dust, the cross joint should be installed at the bend point of the pressure tapping for convenient blow washing.