Flowmetering
Gilflo and ILVA flowmeters
Dimensions/weights (approximate) in mm and kg
Sizing the Gilflo ILVA flowmeter
In order to determine the flow capacity of a Gilflo ILVA pipeline unit,
it is necessary to calculate the equivalent water flowrate (Q
E
)
based on the anticipated actual flow (see Step 1).
The Table below is used to select the appropriate unit (steam only).
Step 1.
Determine equivalent water flowrate (Q
E
) in l/min:-
Volumetric units
Size
DN250
DN300
Note:- Pressure tappings are threaded 1⁄4" NPT
A
B
C
D
E
F
Weight
104 204 444
330
35.0 35
41.5
120 250 530
385
42.5 35
67.0
Mass flow units
Q
E
=
q
m
SG
Q=q
1000
E
M
D
F
Q
E
= Q
S
D
S
x
P
F
x
P
F
1000 P
S
T
S
E
D
F
Note: Pressure tappings
(2 off located on one side only)
Liquids
Gases
and steam
actual flow
conditions
Gases
standard
conditions
Q
E
= Q
L
SG
D
Q
E
= Q
F
F
Q = Q
D
S
x
P
S
x
T
F
E
S
1 000 P T
1000
Ö
F
S
A
B
q
m
=
Q
L
=
Q
S
=
Q
F
=
SG =
D
S
=
D
F
=
P
S
=
P
F
=
T
S
=
T
F
=
Mass flowrate (kg / min)
Maximum liquid flowrate (litres/min)
Maximum gas flowrate at standard conditions (litres/min)
Maximum gas flowrate at actual flow conditions (litres/min)
Specific gravity
Density of gas at standard conditions (kg / m3)
Density of gas at actual flow conditions (kg / m3)
Standard pressure: 1
.
013 bar a, 1
.
033 kg/cm
2
a, 14.70 psi a
Actual flow pressure in same absolute units as P
S
Standard temperature (K) = °C + 273
Actual flow temperature (K) = °C + 273
Where:
Q
E
= Equivalent water flowrate (litres/min)
C
Safety information, installation and maintenance
For full details see the Installation and Maintenance Instructions
supplied with the product.
Installation note:
The following main points are given here for guidance:
1. The Gilflo ILVA should be mounted with a minimum of 6 straight
pipe diameters upstream and 3 downstream. No valves, fittings
or cross sectional changes are permitted within these pipe
lengths. Where an increase in nominal pipe diameter is required
upstream of the flowmeter, the length of straight pipe should be
increased to 12 diameters. Similarly, where a Gilflo ILVA is
installed downstream of two 90 degree bends in two planes,
a pressure reducing valve or a partially open valve, 12 upstream
pipe diameters should be allowed.
2. It is important that the internal upstream and downstream diameters
of pipe are smooth. Ideally seamless pipes should be used. It is
recommended that slip-on flanges be used to avoid any intrusive
weld beads on the internal diameter of the pipe.
3. Care should be taken to install the Gilflo ILVA concentrically in the
line. If this is not done, flow measurement errors may occur.
4. The Gilflo ILVA should be mounted horizontally. For vertical
installations, consult Spirax Sarco.
Step 2.
Using the value of Q
of the flowmeter.
as determined in Step 1, select
the correct size of the Gilflo ILVA flowmeter using the Table below.
In practice, it will often be the line size that determines the choice
Flowmeter type
DN250
DN300
Max. Q
E
litres / min
7 750
10 975
Maximum pressure drop
Wg
200
200
E
5. For steam applications, good basic steam engineering practices
should be followed:
Example: Determine which Gilflo pipeline unit is required to
measure the flow of compressed air when:
1: Estimated maximum rate of flow = 28000 s m3 /h at 7 bar g and 20°C.
Note: Standard conditions = 1.013 bar a, 0°C giving a standard
density of 1.29 kg / m3
2: Calculate Q
E
from:
D
S
P
S
T
F
Q = Q
x
x D
S
P
F
P
F
E
S
Q
E
=Q
S
x
x
1 000 P T
-
Correct line drainage through adequate trapping.
-
Good alignment and support of associated pipework.
-
Line size changes achieved by the use of eccentric reducers.
Ö
1000 P
S
T
S
F
S
Maintenance note:
There are no user serviceable parts in the Gilflo ILVA. A visual
check together with confirmation that the orifice / cone reference
dimension is within tolerance is possible.
Sizing - Gilflo ILVA flowmeter minimum and maximum saturated steam flowrates in kg / h
Notes:
1. These capacities are based on a differential pressure across the flowmeter of 498 m bar H
2
0 (200 Inches).
2. Minimum flow is 1% of maximum (100:1 turndown).
3. The table below is a guide only.
Q
E
7 750
78
10 975
110
15 985
160
22 637
226
22 185
222
31 417
314
26 915
269
38115
381
30 899
309
43 758
438
Q
E
=(28000 x 16.667) x
Q
E
= 6 174 litres / min
So a DN250 ILVA is recommended.
Note: 1 m3 / h = 16.667 litres / min
1.29
x
1.013
x
293
36 043
433
51 042
510
39 099
391
55 369
554
43 292
433
61 307
613
49 541
495
70 157
702
1 000
8.013 273
Size
DN250
DN300
Max.
Min.
Max.
Min.
Steam pressure bar g
1
3
5
7
10
12
15
20
25
30
40
69 758
698
98 778
988
55 155
552
78 107
781
60 325
603
85 428
854
How to order example:
1 off Spirax Sarco DN250 ILVA flowmeter suitable for fitting between EN 1092 PN16 connections.
TI-P337-46 MI Issue 3
Gilflo ILVA Flowmeter DN250 and DN300
3.2.6
