PD Flow Meter is referred to as positive displacement flowmeter. Helical Gear-PD Flow Meter is also called, spiral double rotor flowmeter, LLT, LZ double rotor flowmeter or UF-Ⅱ spiral rotor flowmeter.

Features of Helical Gear-PD Flow Meter

1. Notable features such as no pulsation, extremely low noise, high precision, high reliability, large flow, and strong environmental adaptability.
2. The spiral rotor flowmeter can indicate cumulative flow, instantaneous flow, single flow, etc. on site.
3. It can output pulse signal, 4-20mA or 1-5V analog signal, 4-20mA+HART, MODBUS, support 232,485 communication, etc.
4. Combined with mechanical batch controller or electronic batch controller, it can realize various functions such as different types of filling and batch control.
5. The spiral rotor rotates at a constant speed in the metering cavity, and the flow is constant.
6. The spiral rotor rotates at a constant speed and the fluid pulsation is small.
7. The sending pulse is stable and accurate.
8. Various counters, speed regulators and external fine regulators can be configured.
9. Can be installed vertically (limited to DN200 or less, please specify when ordering)
10. It is suitable for thin oil, light oil, heavy oil, crude oil with large sand content and large water content, and the measured liquid has a large viscosity range.
11. The flow of liquid through the flowmeter is large, and the maximum flow is about twice that of an ordinary volume meter with the same diameter.
12. Long service life, high accuracy and strong reliability.
13. The internal pressure loss is extremely small.
14. The longest distance of wired remote transmission is 1000 meters, pulse signal output N=0.1L (one pulse is 1N), and it can be directly connected to the computer.
15. Intrinsically safe explosion-proof IaⅡCT6 (intrinsically safe type); explosion-proof dⅡBT6 (explosion-proof type); protection IP56.

Read more about Everything You Need To Know About Electronic Flow Meters

Specifications of Helical Gear-PD Flow Meter

Technical Parameters

Nominal diameter (mm)	8-400
Accuracy	0.2/0.5 level
Pressure loss	0-1000mPa.s‹80KPa; 1000-20000mPa.s‹150KPa
Nominal pressure	1.6, 2.5, 4.0, 6.4MPa
temperature range	-20℃-+80℃, +80℃+150℃, +150℃-+250℃
Medium viscosity	0-2000mPa.s
Ambient temperature	-30℃-+70℃
Connecting flange	GB9115.0719-2000 JB/TB2-94; It can also be manufactured according to user-specified flange standards
Photoelectric pulse (current) converter	Explosion-proof mark: ExdⅡBT4 ExdⅡBT4 (excluding acetylene)
Electronic counter	Explosion-proof mark: ExdⅡBT4 (without acetylene)
Protection level	IP65

Extended reading: Orifice Plate Flow Meter

Material selection

Model	Shell, front cover, back cover	Cover	Spiral rotor	Shaft	Shaft sleeve	Nominal pressure (MPa)
LLT-E	Cast steel	cast iron	Cast iron, aluminum alloy, stainless steel	stainless steel	Graphite, rolling bearings	Below DN100 -4.0 Above DN150-2.5
LLT-B、C	stainless steel	stainless steel		stainless steel		1.6、2.0、2.5
LLT-S	Double body type flowmeter; Specifications are DN80, DN100, DN150; Nominal pressure 6.3MPa, DN200 nominal pressure 4.0MPa
Note	The material of LLT-C is OCr18Ni12Mo2Ti; The material of LLT-B is OCr18Ni9Ti; Special requirements can be specially designed.

Flow range (m³/h)

Table 1, Accuracy 0.5

Model	Diameter	Viscosity mPa.s
		0.3~0.8	0.8~2	2~15	15~400	400~1000	1000~2000	2000~3500
		Petrol	Kerosene	Diesel, engine oil	Heavy oil	High viscosity liquids
LLT-0252	25	3~9	1.5~10	1~10	1~10	1~8	1~8	1~6
LLT-0401	40	3~9	1.5~10	1~10	1~10	1~8	1~8	1~6
LLT-0402		7~20	3~22	2.5~25	2.5~25	2~18	2~18	3~12
LLT-0501	50	7~20	3~22	2.5~25	2.5~25	2~18	2~18	3~12
LLT-0502		9~36	4.5~36	3.6~36	3.6~36	2.8~25	2.8~25	4.5~18
LLT-0801	80	9~36	4.5~36	3.6~36	3.6~36	2.8~25	2.8~25	4.5~18
LLT-0802		20~80	10~80	10~100	10~100	6.5~56	6.5~56	5~40
LLT-1001	100	20~80	10~80	10~100	10~100	6.5~56	6.5~56	5~40
LLT-1002		25~100	18~100	15~150	15~150	8.5~80	8.5~80	6.5~55
LLT-1501	150	25~100	18~100	15~150	15~150	8.5~80	8.5~80	6.5~55
LLT-1502		55~225	30~250	25~250	25~250	18~150	18~150	10~100
LLT-2001	200	55~225	30~250	25~250	25~250	18~150	18~150	10~100
LLT-2002		90~360	50~400	40~400	40~400	28~240	28~240	20~160
LLT-2501	250	90~360	50~400	40~400	40~400	28~240	28~240	20~160
LLT-2502		130~540	65~540	60~600	60~600	42~360	42~360	30~240
LLT-3001	300	130~540	65~540	60~600	60~600	42~360	42~360	30~240
LLT-3002		220~800	110~900	95~950	95~950	70~600	70~600	54~450
LLT-3501	350	220~800	110~900	95~950	95~950	70~600	70~600	54~450

Table two, Accuracy level 0.2

Model	Diameter	Viscosity mPa.s
		0.3~0.8	0.8~2	2~15	15~400	400~1000	1000~2000	2000~3500
		Petrol	Kerosene	Diesel, engine oil	Heavy oil	High viscosity liquids
LLT-0252	25	3.5~8	3~10	2~10	2~10	2~8	2~8	2~6
LLT-0401	40	3.5~8	3~10	2~10	2~10	2~8	2~8	2~6
LLT-0402		8~20	5.5~22	4.5~22	4.5~22	4~18	4~18	3~12
LLT-0501	50	8~20	5.5~22	4.5~22	4.5~22	4~18	4~18	3~12
LLT-0502		15~36	9~36	7~36	7~36	6~25	6~25	4.5~18
LLT-0801	80	15~36	9~36	7~36	7~36	6~25	6~25	4.5~18
LLT-0802		30~80	20~80	15~80	15~80	14~56	14~56	10~40
LLT-1001	100	30~80	20~80	15~80	15~80	14~56	14~56	10~40
LLT-1002		40~100	25~100	20~120	20~120	18~72	18~72	14~55
LLT-1501	150	40~100	25~100	20~120	20~120	18~72	18~72	14~55
LLT-1502		88~220	57~225	44~220	44~220	38~150	38~150	25~100
LLT-2001	200	88~220	57~225	44~220	44~220	38~150	38~150	25~100
LLT-2002		150~360	90~360	72~360	72~360	50~210	50~210	40~160
LLT-2501	250	150~360	90~360	72~360	72~360	50~210	50~210	40~160
LLT-2502		180~540	135~540	100~540	100~540	90~360	90~360	60~240
LLT-3001	300	180~540	135~540	100~540	100~540	90~360	90~360	60~240
LLT-3002		250~800	220~900	180~900	180~900	150~600	150~600	110~450
LLT-3501	350	250~800	220~900	180~900	180~900	150~600	150~600	110~450

Remarks: For special requirements, class 0.3 and class 0.1 flowmeters can be provided

Read more about: Industrial Oil Flow Meters

How does a PD meter work?

The flow meter is mainly composed of a body, a pair of spiral rotors, a magnetic coupling, a reduction mechanism, an adjusting gear, a counter and a signalling device.

The number of revolutions of the spiral rotor is transmitted to the meter head counter through a reduction mechanism composed of a magnetic coupling and a series of gears.

The magnetic coupling is mainly composed of active magnetic steel and driven magnetic steel. The use of magnetic coupling can increase the working pressure and working temperature of the flowmeter, ensure safe operation, and reduce maintenance work.

Extended reading: Positive Displacement Flow meter Technology

The measurement chamber mainly has a sealed cavity formed by a pair of special rotors and cover plates as the flow measurement unit.

The rotor is driven by the pressure difference between the inlet and outlet of the flowmeter to rotate, so as to continuously measure the liquid at the inlet to the outlet after being measured in the sealed cavity.

The amount of liquid flowing through each revolution is eight times that of the sealed cavity in the figure. The total number of rotor rotations and the speed of rotation are transmitted to the counting mechanism by the sealed coupling. Then there is pointer display and word wheel accumulation, you can know that it passes through the pipeline Total amount of liquid.

A pulse transmitter can also be installed in the counting mechanism, which becomes a flow meter with a signal.

Matching with the company’s electric display instrument, it can realize remote transmission (quantity, accumulation, instant and other functions) automatic measurement and control.

Read more about: Liquid Flow Meters Guide

Gear types of PD flowmeter:

SPUR GEAR

In Spur gear positive displacement flow meters, fluid travels around two round gears and is pushed through the meter’s internal chamber from inlet to outlet. The discrete volume of liquid trapped between each gear tooth is measured, as opposed to the Oval gear meter where a much larger volume between gears is swept through the chamber.

HELICAL GEAR

Possibly the most accurate PD meter in which two intersecting cylindrical bores are fitted with two interlocking helical screw-shaped gears. Because gear orientation is inline with flow, as the fluid passes through, the gears rotate with very little pressure drop. These flow meters are highly accurate over wide flow ranges and are compatible with very high viscosity fluids.

ROTARY PISTON

In this design a rotary piston oscillates in the circular internal chamber displacing a fixed amount of fluid with each rotation. This style accommodates ultra low flows and high flows, as well as high pressures.

Extended reading: Cylinder Gear flow meter for micro flow measurement.

More Featured PD Flow Meters

Sino-Inst, Manufacuturer for Helical Gear-PD Flow Meters. For example: crude oil flowmeter, diesel flowmeter, gasoline flowmeter.

Sino-Inst’s Helical Gear-PD Flow Meters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, US, and other countries.