Application of Oval Gear Flow Meters in Ship Manufacturing

Digital High-Precision Oval Gear Flowmeter

Structure and Operation Principle

The oval gear flowmeter consists of a flow transmitter and a counting mechanism. If a radiator is installed between the transmitter and the counting mechanism, a high-temperature flowmeter is formed. The transmitter is composed of a metering chamber containing a pair of oval gear rotors and a sealed coupling, while the counting mechanism includes a reduction gear, an adjustment mechanism, a counter, and a signal transmitter.

Inside the metering chamber, a pair of oval gears and cover plates form a crescent-shaped cavity which serves as the unit of flow measurement. The oval gears are driven to rotate by the pressure difference between the inlet and outlet of the flowmeter, thereby continuously measuring the liquid through the crescent-shaped cavity and delivering it to the outlet. The volume of liquid passing through per revolution is four times that of the crescent-shaped cavity. The sealed coupling transmits the total number of rotations and the rotational speed of the oval gears to the counting mechanism or signal transmitter, thus allowing the total volume and instantaneous flow rate of the liquid passing through the pipeline to be determined.

Materials of main parts and the nominal operating pressure

	Shell andcover	cover plate	oval wheel	Rotaryshaft	bushing	Nominal pressure（MPa）
LC-A	Cast steel	Cast	Cast iron 、Stainless steelAlloy aluminum,engineering material	Stainlesssteel	Bronze(with oil) or rolling bearing	1.6
LC-E	Cast steel	Cast iron			Bronze(with oil) or rolling bearing	Under DN50 6.3 DN80- 100 4.0 6.3 DN150-200 2.5
LC-Q	Cast iron	Cast iron			Bronze(with oil) or rollingbearing ，graphite	1.6
LC-B	Stainless steel	Stainless steel	Stainless steel		Bronze(with oil)、 graphite 、 rolling bearing	1.6

Flow range:

unit: m3/h

Type	DN	Viscosity (mPa. s)
Type	DN	<0.3	0.3~0.8	0.8~2	2~200	200~ 1000	1000~2000
LC- 10II	10		0.08-0.25	0. 1-0.25	0.05-0.25	0.08-0.25	0.05-0.25
LC- 10	10		0.2-0.5		0.08-0.5	0.08-0.5	0.05-0.5
LC- 15	15		0.75-1.		0.3- 1.5	0.3- 1.5	0. 15- 1.5
LC-20	20		1.5-3	1-3	0.5-3	0.5-3	0.3-3
LC-25	25	4-6	3-6	2-6	1-6	1-6	0.6-6
LC-40	40	9- 15	7.5- 15	5- 15	2.5- 15	2.5- 15	1.5- 15
LC-50	50	10-24	8-24	8-24	4.8-24	4.8-24	2.4-24
LC-B40、50	40 、50	8-20	6-20	6-20	4-20	4-20	2-20
LC–65	65	27-40	20-40	15-40	8-40	8-40	4-40
LC-80	80	40-60	30-60	20-60	12-60	12-60	6-60
LC- 100	100	67- 100	50- 100	34- 100	20- 100	20- 100	10- 100
LC- 150	150	127- 190	95- 190	64- 190	38- 190	38- 190	19- 190
LC-200	200	227-340	170-340	114-340	56-340	56-340	34-340
Accuracy		0.5	0.5	0.2	0.5	0.2	0.5

Installation and Operation

1. A strainer should be installed in front of the meter, and be sure that the arrows on the casting of the meter and the strainer pointing the same direction of the liquid flow.

2. If the metered media contains gas, a gas separator should be installed in front of the meter.

3. Whether the pipe line is vertically or horizontally installed, the wheel’s shaft of the meter must be fixed horizontal, that is, the dial is vertical to the surface.

4. While the meter is installed properly, the counter may be turned 180°or 90°for easy reading.

5. Prior to the installation of the new meter, first push the oval wheels from the outlet for several times with a bamboo rod, if the wheels don’t move, they can be immersed in the petrol to prevent from deposits in the meter after the factory’s inspection.

6. A throttle valve must be fixed at the inlet of the meter, an on-off valve at the outlet, which must be slowly activated to prevent from a sudden impact, reverse flow, and water hammer.

7. It is forbidden to clean the meter with steam.

8. For the continuous operated departments, a by-pass should be mounted.

9. Prior to the installation of the meter, the pipe line must be thoroughly cleaned,and at the time of cleaning use a straight pipeline in stead of the meter,to prevent impurity、welding residue from entering the meter.

10. It is forbidden to inspect the meter made of cast iron and cast steel using water.

11. During the operated of the meter the flow rate can’t exceed the flow marked on the mamelon plate. It is preferable to operate the meter at 50—80% of the max. flow.

12. If the metered media is causticity,stainless steel shall be selected.

13. Following is the installation figure.