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orifice flow meter from premier

orifice flow meter from premier

10-10-2026

LG Series Orifice Flow Measurement Throttle Device

Summary

Throttle device is the most historic and most extensively used flow measurement instrument. Its features are simple structure, easy installation, stable performance and high accuracy, etc merits. It can be used for flow measurement for liquid, steam and gas in modern industries. There are many kinds of throttle devices with a whole variety (being conformability with Standard GB/T2624-2006, Standard ISO5167- 1-20031, Standard BS1042- 1989 and Standard ASME) that are manufactured with advanced calculation methods and precise manufacturing means. They are applied extensively in petroleum, chemical, power, light industry, water supply field, gas transmission field etc.

Principle of operation

A throttle element (like throttle orifice, throttle nozzle, etc) is installed in a pipe that is full of one way flowing continuous fluid. When the fluid passes the throttling orifice of the throttling element, the fluid stream forms local shrink. Then the velocity increases, so does the kinetic energy, the static pressure decreases. So, there is a differential static pressure from the fore and the rear of the throttle element, i.e. △P=P1-P2. If the area of the throttle orifice is F, the mass flow of the fluid is qm, the volume flow

Orifice Throttling Device

Wenturi Tube Throttling Device

is qv the density is ρ, then according to the flow continuity law and Bernoulli equation, the following mathematical relations between differential pressure and fluid flow can be derived:

qm = αF ·Δpp or qv =

“α” is flow coefficient. According to the above equation, if the area of the throttle orifice and fluid density are constant, flow has direct ratio with square root of differential pressure. That is to say, if you have the differential pressure value, then you can calculate the flow value. Throttle device can measuring fluid flow just according to this principle.

LG Series Orifice Flow Measurement Throttle Device

Model composition and meaning

LG □ □ --- □ □ □

Series number

Table 1 Throttling element code and meaning

Code	Meaning	Code	Meaning
Y	Standard orifice plate	I	Eccentric orifice plate
Q	1/4 circle orifice plate	S	Segmental orifice plate
X	Small caliber orifice plate	Z	Raw cast contracted section (throat) Classic Venturi Tube
T	Taper inlet orifice plate	J	Machined contracted section (throat) Classic Venturi Tube
M	ISA1932 ejection nozzle	H	Iron plate welded contracted section (throat) Classic Venturi Tube
C	Major diameter ejection nozzle	W	Venturi ejection nozzle

Table 2 Pressure measuring code and meaning

Code

Meaning

Pressure

measuring

with flange

Pressure

measuring with

angle joint ring

chamber

Pressure

measuring

with drilling

hole

Pressure measuring

with two distanced

holes

Special

pressure

measuring

Table 3 Nominal diameter code and meaning

Code				01		016		02		026		03	04	05	06	08	10
DN			mm	10		15		20		25		32	40	50	65	80	100
			in			1/2		3/4		1		1- 1/4	1- 1/2	2	2- 1/2	3	4

Code				12		15		20		25		30	35	40	45	50	60
DN	mm			125		150		200		250		300	350	400	450	500	600
	in			5		6		8		10		12	14	16	18	20	24
Code					70		80		90		91
DN		mm			700		800		900		1000

Table 4 Nominal pressure code and meaning

Code		01	02	03	04	05	06	10	11	15	16
PN	MPa	1.6	2.0	2.5	4.0	5.0	6.3	10.0	11.0	15.0	16.0
PN	Class		150			300			600	900

Code		25	26	42
PN	MPa	25.0	26.0	42.0
PN	Class		1500	2500

Table 5 Straight pipe section code and meaning

Code

Meaning

Throttle

element

Throttle

element, with

flange

Throttle

element, with

flange, with

upper and

lower straight pipe section

Throttle

element, with

flange, with

upper and

lower straight

pipe section,

with upper and lower

connection flange

Throttle

element, with

flange, with

upper and

lower straight

pipe section,

with upper connection

flange

Throttle

element, with

flange, with

upper and

lower straight

pipe section,

with lower

connection flange

Welding

structure

2. Standards

2. 1. Standards for throttle element

Table 6 Standards for throttling element

Code	Meaning	Standards code
Y	Standard orifice plate	GB/T2624-2006 (ISO5167-2003)
Q	1/4 circle orifice plate	BS1042- 1989
X	Small caliber orifice plate	GB2624-2006
T	Taper inlet orifice plate	BS1042- 1989
M	ISA1932 nozzle	GB/T2624-2006 (ISO5167-2003)
C	Major diameter nozzle	GB/T2624-2006 (ISO5167-2003)
I	Eccentric orifice plate	ASME
S	Segmental orifice plate	ASME
Z	Raw cast contracted section (throat) Classic venturi Tube	GB/T2624-2006 (ISO5167-2003)
J	Machined contracted section (throat) Classic venturi Tube	GB/T2624-2006 (ISO5167-2003)
H	Iron plate welded contracted section (throat) Classic venturi Tube	GB/T2624-2006 (ISO5167-2003)
W	venturi nozzle	GB/T2624-2006 (ISO5167-2003)

2.2 Flange & Gasket standards

Standards for flanges and gaskets: you can select JB Standard, HG20592 ~ 20614-2009 (European system), HG20615-20635-2009 (American system) or other standards1. Application range for

throttling elements

LG Series Orifice Flow Measurement Throttle Device

Installation dimensions of throttle device

1. 1.0-6.3 MPa installation dimensions of throttle device with flange pressure measuring

1. Flowing direction 2. Holeφ23 to be connected to the pressure measuring tube φ22

LG Series Orifice Flow Measurement Throttle Device

1.0MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	126	276	422
	15	95	126	351	497
	20	105	128	428	586
	25	115	132	507	673
	32	135	132	612	786

	40	145	138	738	924
	50	160	139	889	1075
	65	180	141	1116	1314
	80	195	146	1346	1552
	100	215	146	1646	1860

	125	245	159	2034	2280
	150	280	159	2409	2655
	200	335	163	3163	3417
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	390	166	3166	3432
	300	440	162	3162	3428
	350	500	164	3164	3430
	400	565	164	3164	3430
	450	615	176	3176	3462

	500	670	190	3190	3508
	600	780	212	3212	3578
	700	895	210	3210	3576
	800	1010	238	3238	3668
	900	1110	242	3242	3680
	1000	1220	242	3242	3680

LG Series Orifice Flow Measurement Throttle Device

1.6MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	122	272	418
	15	95	122	347	493
	20	105	128	428	586
	25	115	132	507	673
	32	135	132	612	786

	40	145	138	738	924
	50	160	145	895	1093
	65	180	145	1120	1326
	80	195	146	1346	1560
	100	215	146	1646	1860

	125	245	159	2034	2280
	150	280	159	2409	2655
	200	335	159	3159	3413
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	405	168	3168	3446
	300	460	168	3168	3454
	350	520	178	3178	3496
	400	580	149	3194	3560
	450	640	206	3206	3592

	500	705	212	3212	3610
	600	840	226	3226	3652
	700	910	238	3238	3684
	800	1020	248	3248	3714
	900	1120	266	3266	3760
	1000	1255	272	3272	3778

LG Series Orifice Flow Measurement Throttle Device

2.5MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	122	272	418
	15	95	122	347	493
	20	105	128	428	586
	25	115	132	507	673
	32	135	132	612	786

	40	145	138	738	924
	50	160	145	895	1093
	65	180	145	1120	1326
	80	195	146	1346	1560
	100	230	184	1684	1938

	125	270	197	2072	2350
	150	300	205	2455	2749
	200	360	221	3221	3547
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	425	232	3232	3578
	300	485	246	3246	3620
	350	550	260	3260	3658
	400	610	294	3294	3760
	450	660	296	3296	3762

	500	730	306	3306	3792
	600	840	326	3326	3852
	700	955	348	3348	3914
	800	1070	368	3368	3974

LG Series Orifice Flow Measurement Throttle Device

4.0MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	114	264	404
	15	95	114	339	479
	20	105	116	416	560
	25	115	120	495	647
	32	135	134	614	794

	40	145	138	738	930
	50	160	135	885	1077
	65	180	151	1126	1334
	80	195	148	1348	1580
	100	230	164	1664	1936

	125	270	161	2036	2308
	150	300	165	2415	2703
	200	375	181	3181	3533
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	445	208	3208	3616
	300	510	236	3236	3700
	350	570	246	3246	3726
	400	655	290	3290	3858
	450	680	300	3300	3884
	500	755	320	3320	3944

LG Series Orifice Flow Measurement Throttle Device

6.3MPa	Nominal diameter DN	D	LA	LB	LC
	10	100	136	361	553
	15	105	136	286	478
	20	125	148	448	672
	25	135	148	523	755
	32	150	152	632	880

	40	165	166	766	1038
	50	175	167	917	1197
	65	200	173	1148	1448
	80	210	170	1370	1670
	100	250	176	1676	1996

	125	295	205	2080	2472
	150	340	221	2471	2903
	200	405	235	3235	3699
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	470	248	3248	3736
	300	530	276	3276	3820
	350	595	314	3314	3930
	400	670	346	3346	4026

2. 1.0-6.3 MPa installation dimensions of throttle device with ring chamber pressure measuring

1. Flow direction

LG Series Orifice Flow Measurement Throttle Device

1. Flow direction

1.0MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	129	279	425
	15	95	129	354	500
	20	105	135	435	593
	25	115	139	514	680
	32	135	143	623	797

	40	145	149	749	935
	50	160	149	899	1085
	65	180	155	1130	1328
	80	195	160	1360	1566
	100	215	164	1664	1878

	125	245	181	2056	2302
	150	280	181	2431	2677
	200	335	185	3185	3439
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	390	192	3192	3458
	300	440	192	3192	3458
	350	500	194	3194	3460
	400	565	194	3194	3460
	450	615	206	3206	3492

	500	670	222	3222	3540
	600	780	246	3246	3612
	700	895	248	3248	3614
	800	1010	280	3280	3710
	900	1110	288	3288	3726
	1000	1220	288	3288	3726

LG Series Orifice Flow Measurement Throttle Device

1.6MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	129	279	425
	15	95	129	354	500
	20	105	135	435	593
	25	115	139	514	680
	32	135	143	623	797

	40	145	149	749	935
	50	160	155	905	1103
	65	180	159	1134	1340
	80	195	164	1364	1578
	100	215	164	1664	1878

	125	245	181	2056	2302
	150	280	181	2431	2677
	200	335	185	3185	3439
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	405	198	3198	3476
	300	460	202	3202	3488
	350	520	220	3220	3538
	400	580	244	3244	3610
	450	640	256	3256	3642

	500	705	262	3262	3660
	600	840	276	3276	3702
	700	910	288	3288	3734
	800	1020	298	3298	3764
	900	1120	316	3316	3810
	1000	1255	322	3322	3828

LG Series Orifice Flow Measurement Throttle Device

2.5MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	129	279	425
	15	95	129	354	500
	20	105	131	431	581
	25	115	135	510	668
	32	135	149	629	815

	40	145	155	755	953
	50	160	155	905	1103
	65	180	163	1138	1352
	80	195	170	1370	1596
	100	230	184	1684	1938

	125	270	197	2072	2350
	150	300	205	2455	2749
	200	360	221	3221	3547
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	425	232	3232	3578
	300	485	246	3246	3620
	350	550	260	3260	3658
	400	610	294	3294	3760
	450	660	296	3296	3762

	500	730	306	3306	3792
	600	840	326	3326	3852
	700	955	348	3348	3914
	800	1070	368	3368	3974

LG Series Orifice Flow Measurement Throttle Device

4.0MPa	Nominal diameter DN	D	LA	LB	LC
	10	90	129	279	419
	15	95	129	354	494
	20	105	131	431	575
	25	115	135	510	662
	32	135	149	629	809

	40	145	155	755	947
	50	160	155	905	1097
	65	180	175	1150	1358
	80	195	176	1376	1608
	100	230	196	1696	1968

	125	270	197	2072	2344
	150	300	205	2455	2743
	200	375	237	3237	3589
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	445	266	3266	3674
	300	510	294	3294	3758
	350	570	304	3304	3784
	400	655	348	3348	3916
	450	680	358	3358	3942
	500	755	378	3378	4002

LG Series Orifice Flow Measurement Throttle Device

6.3MPa	Nominal diameter DN	D	LA	LB	LC
	10	100	155	305	497
	15	105	155	380	572
	20	125	171	471	695
	25	135	175	550	782
	32	150	183	663	911

	40	165	195	795	1067
	50	175	199	949	1229
	65	200	209	1184	1484
	80	210	210	1410	1710
	100	250	220	1720	2040

	125	295	257	2132	2524
	150	340	277	2527	2959
	200	405	293	3293	3757
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	470	306	3306	3794
	300	530	323	3323	3867
	350	595	372	3372	3988
	400	670	404	3404	4084

3. 10.0- 16.0 MPa installation dimensions of throttle device with flange pressure measuring

1. Flow direction

LG Series Orifice Flow Measurement Throttle Device

10.0MPa	Nominal diameter DN	D	LA	LB
	10	100	140	290
	15	105	142	367
	20	125	154	454
	25	135	154	529
	32	150	162	642

	40	165	174	774
	50	195	195	945
	65	220	203	1178
	80	230	206	1406
	100	265	226	1726

	125	310	258	2133
	150	350	288	2538
	200	430	318	3318
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	500	369	3369
	300	585	419	3419
	350	665	457	3457
	400	715	477	3477

LG Series Orifice Flow Measurement Throttle Device

16.0MPa	Nominal diameter DN	D	LA	LB
	10	110	138	363
	15	130	144	444
	20	140	140	515
	25	165	146	626
	32	175	152	752

	50	215	229	956
	65	245	236	1211
	80	260	247	1477
	100	300	267	1767

	125	355	308	2183
	150	390	343	2593
	200	480	404	3404
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	580	493	3493
	300	665	592	3592

4. 26.0-42.0 MPa installation dimensions of throttle device with flange pressure measuring

1. Flow direction

LG Series Orifice Flow Measurement Throttle Device

26.0MPa	Nominal diameter DN	D	LA	LB	LC
	15	120	160
	20	130	174
	25	150	172
	32	160	172
	40	180	186

	50	215	226
	65	245	232
	80	270	259
	100	310	271

	125	375	334
	150	395	370
	200	485	457
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	585	540
	300	675	607

42.0MPa	Nominal diameter DN	D	LA	LB	LC
	15	135	170
	20	140	178
	25	160	196
	32	185	212
	40	205	244
	50	235	276
	65	270	292
	80	305	363
	100	355	410
	125	420	493
	150	485	589
	200	550	674
	For the above table, the length of the front straight section should be 10 times as long as the nominal diameter, the length of the rear straight section should be 5 times as long as the nominal diameter; For the below table, the length of the front straight section should be 2000mm, the length of the rear straight section should be 1000mm.
	250	675	884
	300	760	978

LG Series Orifice Flow Measurement Throttle Device

5. Other throttle device

5. 1 Nozzle

Angle joint ring chamber pressure taking is adopted for installation dimensions of ISA1932 nozzle and Wenturi nozzle, see the table of “ 1.0-6.3 MPa installation dimensions of throttle device with ring chamber pressure measuring”.

Distanced holes pressure taking is adopted for installation dimensions of major diameter ejection nozzle, see the table of “26.0-42.0 MPa installation dimensions of throttle device with flange pressure measuring”.

5.2 Venturi tube

This device is high accuracy, performance stable, low pressure lost (normally is 5% ~ 20% of differential pressure) and easy to maintain. Especially in current energy saving condition, it is measured accurately and energy decreasing, etc, so has widely use in application.

D – inner diameter of pipe (mm); d – inner diameter at throat section (contract section) of Venturi tube (mm)

5.3 Welding throttle device

It is one kind of throttle device, simple structure, cost saving, short production time and no leakage, etc. Especially for measuring industrial high temperature, fluid flow in high pressure pipe and steam flow.

Installation dimensions

LG Series Orifice Flow Measurement Throttle Device

Order requirements

1. When purchasing throttle device, please fill in the specification table of throttle device (see below)

				Throttle Device Parameters Table			Project NO.
							Table NO.
							Page. Total.
Data					Calculation
Operation conditions	Fluid name				Throttle element type
	Operating temperature ℃				Pressure taking type
	Operating pressure MPa				Select scale
	Flow	Liquid kg/h	Max.		Select differential pressure kPa
		Steam kg/h	Nor.		Min. flow limit
		Gas(standard) Nm3/h	Min.		Reynolds number Re (normal flow)
		Liquid kg/m3			Area expansion correction coefficient Fa
		Steam kg/m3			Expansion coefficient ε
		Gas (standard) kg/m3			Flow coefficient α
					Uncertainty %
					Permanent pressure loss Pa
					Diameter ratio βt
					Hole diameter of throttle mm element or segmental height
					1/4 circle radius or eccentricity degree mm
	Operating density kg/m3				Throttle device standard
	Dynamic viscosity mPa.s
	Kinematic viscosity mm2/s				Specification
	Relative humidity (Φ)
	Compression coefficient (Z)				Model
	Isentropic exponent (cp/cv)				Normal diameter (DN)
	Allowable pressure loss Pa				Normal pressure (PN) MPa
Pipe	Nominal diameter (DN)				Flange standard
	Pipe instrument number				Flange inner diameter mm
	Outside diameter/inner diameter mm				Structural length mm
	Material				Pressure tape size mm
					Pressure tape location
					material	Throttle element
						Flange
						Bolt
						Nut
						Gasket
Remark

LG Series Orifice Flow Measurement Throttle Device

2. We supply the following services:

2. 1 To supply different kinds of the above mentioned throttle device in set.

2.2 To supply calculation for the throttle device that the customer owns, including:

1) The diameter of the open pore of throttle element d20 and the instrument recommended flow value are known, on new working conditions, calculate upper limit Hmax of the new differential pressure of the instrument.

2) The diameter of the open pore of throttling element d20, the upper limit Hmax of the instrument differential pressure and the original instrument recommended flow value, calculate new instrument recommended flow value on new working conditions.

2.3 According to the customer’s requirements or drawings, to manufacture the throttle devices.

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