Vent Terminals.

“Ideal” venting (as designed in accordance with IGEM SR/25 allows significant reductions in the extent of a hazardous area around the vent discharge point. Pressure relief valves will have at their vent terminal a Zone 1 sphere of about 1 m. Different Codes give a range of options for the rest of the zoning. One document gives a Zone 2 sphere of not more than 260 times the vent diameter. Sitting on top of the vent will be a cone of basal diameter 350D and a height of the Zone 2 radius. Another gives a number of cylindrical shapes, the dimensions of which depend on the vent orifice diameter and the flow of venting gases.

Where the design dispersion is not ideal, the use of the spherical approach is typical. In this case, the outer Zone 2 sphere may have a radius of 45.6 M^0.55 where M is the mass flow rate in kg/s.

Careful vent design is necessary to achieve “ideal venting. A flame trap must not be used at this point and consideration must be given to good dispersion. Therefore, the design of the vent terminal to keep out the weather is of paramount importance if we are to attempt to remain within the constraints of an `ideal' vent.

GEA has available three sizes of vent termination all designed to ensure good safe dispersion of venting gases whilst ensuring minimal water ingress.

The larger terminal is intended for pressure relief and vent systems and comes in 1½" [VT40] and 2" bsp [VT 50] sizes. These are made of aluminium and include a stainless steel bug trap.

The smaller vent terminal has been designed to meet the needs of National Grid Transco document E28 and satisfies the requirements of GM8 Part 1 Breathers. This is of stainless steel construction and the flow rate can be designed to meet flows at 2.5, 10 or 15 m3/h by changing the internal jet bore. It is available with a ½" bsp threaded connection.

This 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 VT 15 assists in reducing emissions and any hazardous area as required by IGE SR/25 and DSEAR.

For vents needing in-line flame arrestors, GEA has a compact lightweight unit FA15 which has 1" inlet and ½" bsp outlet connections.

The vent terminals VT40, VT50 and VT75 may not be suitable for some higher pressure applications, please discuss your application with GEA before ordering.