3.1.0.18 Edition 04.10Technical Information · GB
www.kromschroeder.com
• For use as a measuring or restricting orifice• Can be combined with valVario valves and regulators• Air and gas flow rate diagrams to facilitate configuration• Easy installation thanks to flanges with internal thread• Replaceable aluminium washers for optimal adjustment to local operating
conditions
Measuring orifice VMO
VMO · Edition 04.10
2
t = To be continued
Table of contentsMeasuring orifice VMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Table of contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1 Examples of application. . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.1 Self recuperative burner for direct heating systems . . . . . . 41.1.2 Continuous control with pneumatic ratio control system . . 4
2 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Flow rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.1 VMO 110, VMO 115, VMO 120, VMO 125. . . . . . . . . . . . . 63.2 VMO 232, VMO 240, VMO 250 . . . . . . . . . . . . . . . . . . . 73.3 kV value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.1 Type code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Project planning information . . . . . . . . . . . . . . . . . . . . . 105.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105.2 Gas line connection . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116.1 Seal set VA 1 – 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116.2 Washer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127.1 Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1.1 VMO..R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137.1.2 VMO..N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137.1.3 VMO 240F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
VMO · Edition 04.10
3
1 Application
The valVario measuring orifice VMO is installed in gas control and safety systems, as well as in air systems used in indus-trial and commercial gas heat generation. It can serve as a restricting orifice when used in conjunction with valVario gas solenoid valves and gas control valves.The test points are located in the measuring orifice housing. The measuring orifice VMO is a good-value alternative in areas where no standardized measuring orifice is required. The replaceable washers with different hole sizes allow the orifice to be adjusted perfectly to the local operating conditions.
Shaft melting furnace
Incineration installation for thermal regenerative flue air purification
VMO · Edition 04.10
4
1 .1 Examples of application1 .1 .1 Self recuperative burner for direct heating systems
EKOVAS..L EKOVMO
BVA+IC
M
LEH LEH
VMO VMO
GEH
Self recuperative burner in a direct heating system with an inductor for evacuating the flue gases from the furnace. The inductor generates a vacuum with a centrally positioned noz-zle and thus draws the flue gases out of the furnace chamber through the burner’s heat exchanger. The measuring orifices VMO are designed to record the gas and air flow rates.
1 .1 .2 Continuous control with pneumatic ratio control system
IC 20 + BVA
VAG
M
BVA
VAS ZIO VMO
EKO
With this type of control, the mixture setting can be maintained over a wide control range while at the same time preventing air deficiency. This type of control is used in melting furnaces in the aluminium industry or in regenerative incineration in-stallations in the environment industry, for example. Here, the measuring orifice VMO is designed to record the gas flow rate.
Application
VMO · Edition 04.10
5
2 Function
Base plate
Plate bracket
WasherHousing
A plate bracket with a washer is placed in the VMO housing. There is a hole in the washer through which gas can flow. For replacing the washer, the base plate of the housing can be removed in order to pull the plate bracket and washer together out of the housing.
VMO · Edition 04.10
6
3 Flow rateThe characteristic curves are measured at the test points at 15°C (59°F) for the individual washers.
3 .1 VMO 110, VMO 115, VMO 120, VMO 125
10 20 30 40 60 1001 2 3 5 81
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
VMO 110, VMO 115
V' [m3/h (n)]1 2 3 4 6 10 20 30
0,8 1 2 3 4 6 10 20
60
30
1
2
3
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
4 m
m
6 m
m
5 m
m
10 20 30 40 60 1001 2 3 5 81
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
V' [m3/h (n)]1 2 3 4 6 10 20 30
0,8 1 2 3 4 6 10 20
60
30
1
2
3
VMO 120
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
6 m
m8
mm
10 m
m12
mm
10 20 30 40 60 1001 2 3 5 81
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
V' [m3/h (n)]1 2 3 4 6 10 20 30
0,8 1 2 3 4 6 10 20
60
30
1
2
3
VMO 125
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
10 m
m
16 m
m
14 m
m
12 m
m20
mm
18 m
m
Legend = natural gas (ρ = 0.80 kg/m3) = propane (ρ = 2.01 kg/m3) = air (ρ = 1.29 kg/m3)
VMO · Edition 04.10
7
3 .2 VMO 232, VMO 240, VMO 250
100 200 300400 600 100010 20 30 50 801
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
V' [m3/h (n)]10 20 30 40 60 100 200 300
8 10 20 30 40 60 100 200
600
300
1
2
3
VMO 232
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
16 m
m
24 m
m
20 m
m
100 200 300400 600 100010 20 30 50 801
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
V' [m3/h (n)]10 20 30 40 60 100 200 300
8 10 20 30 40 60 100 200
600
300
1
2
3
VMO 240
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
24 m
m
20 m
m
32 m
m
28 m
m
16 m
m
100 200 300400 600 100010 20 30 50 801
2
3
4568
10
20
30
40506080
100
∆p [m
bar]
V' [m3/h (n)]10 20 30 40 60 100 200 300
8 10 20 30 40 60 100 200
600
300
1
2
3
VMO 250
0.8
1.2
1.62
2.53
4
8
10
16
2432
0.4
40
∆p [i
nch
WC
]
20
70 100 200 300 700 1000 200050 500V' [SCFH]
30001
34 m
m38
mm
32 m
m
Legend = natural gas (ρ = 0.80 kg/m3) = propane (ρ = 2.01 kg/m3) = air (ρ = 1.29 kg/m3)
Flow rate
VMO · Edition 04.10
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3 .3 kV valueThe measuring orifice is determined using the flow rate dia-gram or by calculation using the kv value.
Measuring orifi ce
Nominalfl ange size
Hole diameterWasher [mm] kV [m3/h]
VMO 110 DN 104 1.45 2.16 3.0
VMO 115 DN 154 1.45 2.16 3.0
VMO 120 DN 20
6 1.08 1.710 2.612 3.8
VMO 125 DN 25
10 2.512 3.714 5.216 6.918 9.020 12.2
VMO 232 DN 3216 7.220 10.524 12.5
VMO 240 DN 40
16 7.120 10.524 15.528 21.732 30.6
VMO 250 DN 5032 28.734 34.338 50.7
V· (n) = Flow rate (standard state) [m3/h]kV = Valve coefficient (see table)∆p = Pressure loss [bar]pa = Outlet pressure (absolute) [bar]
ρn = Density [kg/m3] (air 1.29/natural gas 0.80/propane 2.01/butane 2.71)
T = Medium temperature (absolute) [K]
ExampleWe want to find the hole diameter for the washer and the nominal flange diameter for a measuring orifice VMO.We have the maximum flow rate V· (n) max, the outlet pres-sure pa and the temperature T for the medium of natural gas.V· (n) max. = 37 m3/hpa = 30 mbar = 0.03 bar ⇒pa absolute = 0.03 bar + 1 bar = 1.03 bar∆pmax. = 0.01 bar (desired)T = 20°C ⇒ Tabsolute = 20 + 273 K = 293 K
kv = = 11.1 m3/h· 0.83 · 2930.01 · 1.03
37514
The measuring orifice with the next higher kv value is to be selected (see table): e.g. VMO 125 with a washer hole diam-eter of 20 mm.
Flow rate
VMO · Edition 04.10
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4 SelectionType R N F 05 M 04 05 06 08 10 12 14 16 18 20 24 28 32 34 38VMO 110 – – – – – – – – – – – – –VMO 115 – – – – – – – – – – – – –VMO 120 – – – – – – – – – – – –VMO 125 – – – – – – – – – –VMO 232 – – – – – – – – – – – – –VMO 240 – – – – – – – – – –VMO 250 – – – – – – – – – – – – –
= standard, = available
Order exampleVMO 115R05P05
4 .1 Type codeCode DescriptionVMO Measuring orifi ce1–2 Size–10–50
Without inlet and outlet fl angeNominal inlet and outlet diameter in DN
RNF
Rp internal threadNPT internal threadFlange to ISO 7005
05 pe max 500 mbarM With pressure test points04 – 38 Orifi ce diameter* in mm
* Delivery of washers with individual orifi ce diameter on request.
VMO · Edition 04.10
10
5 Project planning information5 .1 Installation
Installation position: VMO can be installed as required.
When fitting to pressure regulator VAD, VAG or VAV, the base plate must be facing the same direction as the regulator body.
Installation position when using other valVario controls: VMO can be installed downstream of the valVario control or can be fitted as a standalone device in the pipe.
5 .2 Gas line connectionIn order to take accurate measurements of the pressure dif-ferential on the measuring orifice VMO, it must be ensured that there is an undisturbed flow of gas at the inlet and outlet for a distance of ≥ 5 × DN.
≥ 5 DN ≥ 5 DN
VMO · Edition 04.10
11
6 Accessories6 .1 Seal set VA 1 – 3
A B
D
C
Scope of delivery:A 1 x double block seal,B 2 x O-rings (flange),C 2 x O-rings (pressure switch),D 2 x sealing rings (test point).
6 .2 WasherFor installing in the plate bracket of measuring orifice VMO. The hole diameter is engraved on the washer. Supply includ-ing the new seal for the base plate.
Hole diameter Order No.[mm] Suitable for VMO 1 Suitable for VMO 2
4 35457454 –5 35457455 –6 35457456 –8 35457457 –10 35457458 –12 35457459 –14 35457460 –16 35457461 3545746418 35457462 –20 35457463 3545746524 – 3545746628 – 3545746732 – 3545746834 – 3545746938 – 35457470xx* 34339103 34339104
* Hole diameter on request.
VMO · Edition 04.10
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7 Technical dataGas types: natural gas, LPG (gaseous), biologically pro-duced methane (max. 0.1 %-by-vol. H2S) or air; other gases on request.The gas must be dry in all conditions and must not contain condensate.Max. inlet pressure pe: max. 500 mbar (7.25 psig).Ambient temperature: -20 to +60°C (-4 to +140°F), no condensation permitted.Storage temperature: 0 to +40°C (-4 to +104°F).Housing: aluminium.Connection flanges with internal thread: Rp to ISO 7-1, NPT to ANSI/ASME.
VMO · Edition 04.10
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L1
D
H1
F
F
VMO..R, VMO..N
Technical data
7 .1 Dimensions
7 .1 .1 VMO . .R
TypeConnection
DimensionsWeight*
L1 F D H1Rp DN mm mm mm mm kg
VMO 110 3/8 10 30 15 62.7 66 0.245VMO 115 1/2 15 30 15 62.7 66 0.245VMO 120 3/4 20 30 23 62.7 66 0.245VMO 125 1 25 30 23 62.7 66 0.245VMO 225 1 25 34 29 88 82 0.505VMO 232 11/4 32 34 29 88 82 0.505VMO 240 11/2 40 34 29 88 82 0.505VMO 250 2 50 34 29 88 82 0.505
* Without fl anges and connection parts.
7 .1 .2 VMO . .N
TypeConnection
DimensionsWeight*
L1 F D H1Rp DN mm mm mm mm kg
VMO 110 3/8 10 30 15 62.7 66 0.245VMO 115 1/2 15 30 15 62.7 66 0.245VMO 120 3/4 20 30 23 62.7 66 0.245VMO 125 1 25 30 23 62.7 66 0.245VMO 225 1 25 34 29 88 82 0.505VMO 232 11/4 32 34 29 88 82 0.505VMO 240 11/2 40 34 29 88 82 0.505VMO 250 2 50 34 29 88 82 0.505
* Without fl anges and connection parts.
VMO · Edition 04.10
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L1
F
F
D
H1
VMO 240F
Technical data > Dimensions
7 .1 .3 VMO 240F
TypeConnection
DimensionsWeight*
L1 F D H1DN mm mm mm mm kg
VMO 240 40 34 66 88 82 0.505
* Without fl anges and connection parts.
VMO · Edition 04.10
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8 MaintenanceCheck for external tightness at least once per annum, at least twice per annum for operation with biologically produced methane.
VMO · Edition 04.10
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