KST – KROMSCHRÖDER SYSTEM TECHNOLOGY
126.96.36.199.2.1 Low gas protection
Low gas pressure protection to prevent insufficient gas flow shall be fitted.
The low gas pressure protection device has to provide satisfactory and reliable proof of the flow for all operation conditions.1)
The system shall prevent start-up or cause safety shut-down or, in the case of no operator supervision, lockout (see 3.48) in the event of pressure falling below a pre-determined value.
This function shall meet the requirement of the protective system according to 5.7.2 and 5.7.3.
Gas pressure detectors shall comply with EN 1854.
The following chapters are printed with the permission of the DIN Deutsches Institut für Normung e.V. (German Institute for Standardization). For the implementation of the DIN Standard, the version with the most recent issue date is deemed authoritative. This is available from Beuth Verlag GmbH, Burggrafenstrasse 6, 10787 Berlin, Germany.
Our note on this Standard:
1) A low gas pressure protection system restricts the limits of safe operation to a gas pressure which prevents CO formation. “No gas” is not critical but “Too little gas” is dangerous. In this state, the burner burns with a low flame and produces CO. The low gas pressure protection device must thus not have a switching point which is too low.
As switching point, we recommend a value which is just above the minimum required pressure (e.g. in conjunction with an air/gas ratio control: the gas pressure must be minimally above the air pressure; the switching point of the pressure switch (PLZ) is above this).
We recommend a fault lock-out to preclude the possibility of uncontrolled re-cycling (restart).