GEA vent terminals, are designed to ensure good safe dispersion of
venting gases whilst ensuring minimal water and material ingress. The stainless steel SVT
model comes in ½ bsp, 1 bsp (also for use on 1 ½ lines), 2 bsp and 3
flanged sizes and is suitable for terminal pressures up to 20 bar. The smaller SVT15 vent terminal has been designed to meet National
Grid E28 and IGEM/GM/8 Part 1 Breathers requirements. This is of stainless
steel construction and the flow rate can be adjusted to meet flow rates of
2.5, 10 or 15 m3/h by changing the internal jet bore. It is
available with a ½" bsp threaded connection. The SVT15 terminal has been tested by one of UK's
larger gas suppliers and confirmed to be ideally suitable for Medium
Pressure domestic type meter installations. The limitation of vent flows
with the SVT15 assists in reducing emissions and any hazardous area as
required by IGEM/SR/25 and DSEAR.
TECHNICAL
DATA FOR GEA VENT TERMINALS
STV 50 STV 25 STV 15
|
Model |
Flow
Rate m3/h |
Cross
wind condition |
Vertical
distance m |
Horizontal radius m
|
Downwash
radius m |
||
|
XH |
XR |
XK |
|||||
|
50% LEL |
100 % LEL |
50% LEL |
100 % LEL |
||||
|
|
|||||||
|
SVT 15 |
2.5 |
2 m/s |
NA |
NA |
NA |
NA |
0.75 |
|
5 m/s |
0.6 |
0.4 |
1 |
NA |
|||
|
SVT 25 |
10 |
2 m/s |
2 |
0.18 |
0.16 |
0.11 |
1.00 |
|
5 m/s |
0.16 |
0.11 |
4 |
2.4 |
|||
|
SVT 50 |
15 |
2 m/s |
0.31 |
0.22 |
2.2 |
1.3 |
3.00 |
|
5 m/s |
2.2 |
1.3 |
4.4 |
2.6 |
|||
Predicted Zoning areas for GEA Terminals ( For guidance only)
VT 15 conforms to ideal venting parameters and
therefore cross wind conditions are
only quoted for the worst condition.
The flow rates are those achieved under low pressure
flow conditions. At higher pressures
where higher pressure drops may be acceptable, a
smaller terminal will provide better dispersion.
Downwash
Considerations.
Vent pipe terminations are subject to some downward dispersion.
For momentum-driven dispersion,
Downward dispersion exists only when the duration of venting duration exceeds 1 minute
XL = 1 m or 0.2 hs (m) whichever is the greater
hs = height of vent tip above ground level (m)
XL should not exceed Xr
Wind-driven dispersion
This may occur at start-up and shut-down where the radial dispersion distance is represented by Xk
Xk should not exceed Xr
The downward dispersion distance is is the smaller of
XL + 3d (m), where d = nominal diameter of vent (m).
Or XK
Addition
downwash due to nearby structures
Vent pipe terminations which are located close to a structure may be subject to additional downward
dispersion due to downwash.
The criteria determining whether or not downwash exists is:
D < X, or D < 10 m, whichever is the smaller.
D = distance
from the vent to a structure (m)
Xr = horizontal radius of the momentum-driven hazardous area (m).
Additional downward dispersion should be of extent (radius) Xk and a height = 0.25Xk.
(XL + 3d + 0.25 Xk) should not exceed Xk as given in Table 12 of SR/25..