Dungs MPA22 User Manual

Printed in Germany / M-MT-BOS
• Edition11.99 • # 231 763
21 … 112
The valve proving function can be enabled or disabled in parameterisation
mode.
After a power failure or a fault unlock, the gas valves are always subjected to
a leakage check before the burner is started. Otherwise, a leakage check is
always performed after a controlled shut-down of the burner.
Only a gas pressure switch is used to check the gas valves for leaks and
monitor the minimum gas pressure. The gas pressure switch must be con-
nected in the circuit between valve Y2 and valve Y3. A leakage check can thus
be performed without the need for additional devices.
A separate gas pressure switch (GW_VPS) is required to test the gas valves for
leaks. The gas pressure switch must be connected in the circuit between valve
Y2 and valve Y3.
After a controlled shut-down, valve Y3 is closed after a 2-second delay. The
external valve remains open. The test section is thus rendered pressureless.
The gas pressure switch must have switched off (open). Test period V1 for the
first valve (Y2) on the gas side now commences.
During the test period, a pressure sufficient to activate the gas pressure switch
must not build up inside the test section, otherwise a fault shut-down will take
place and the fault code for “valve 1 leaky” displayed.
At the end of test period V1, valve Y2 is opened for 1 s. The gas pressure switch
must switch over within this period of time and indicate the presence of gas
pressure, otherwise all valves are closed and the gas fail-safe program is
executed.
Once the period of time has elapsed, valve Y2 and the external pilot valve are
closed.
During the test period for valve Y3, a pressure drop below the operating point
of the preset minimum gas pressure must not occur, otherwise a fault shut-
down will take place and the fault code for “valve 2 leaky” displayed.
- The volume of gas trapped in between valve Y2 and valve Y3
- The preset pressure switching points
- The gas mains pressure applied
- The permissible leakage rate
Integrated valve proving
system, electronic modu-
lation
■ Valve test, gas burner
■ Gas burner, electronic modula-
tion
■ Gas burner, pneumatic modula-
tion
■ Functional sequence
■ Test times for valve Y2 and valve
Y3 are derived from:

Dungs MPA22 Specifications

General

Brand	Dungs
Model	MPA22
Category	Controller
Language	English