Mankenberg RP 824 Originalbetriebsanleitung Seite 28

Original operating manual
pilot-operated pressure regulators RP 824
18.9 Protecting the back pressure regulator
To protect the back pressure regulator against damage from solid particles carried in the pipeline, a strainer or
filter should be fitted and serviced at regular intervals.
18.10 Valve seat leakage
These valves are no shut-off elements ensuring a tight closing of the valve. In accordance with DIN EN 60534-4
and/or ANSI FCI 70-2 they may feature a leakage rate in closed position in compliance with the leakage classes
II – V:
Leakage class II (metal sealing double seat cone) = 0,5% K value
vs
Leakage class III (metal sealing cone) = 0,1 % K value
vs
Leakage class IV (PTFE seal cone)= 0,01 % K value
vs
-5
Leakage class V (soft seal cone) = 1,8 x 10 x Δp x D* [l/h]
*D=seat diameter
Any low leakage requirement must be expressly specified when ordering. Valve leakage can be considerably
reduced by special measures such as lapping the valve seat, using special cone seals and increasing the
control (diaphragm) surfaces.
18.11 Cut-off
For the purpose of installation, servicing and isolation of the valve, shut-off valves should be installed upstream
and downstream of the back pressure regulator. When closing the shut-off valves the upstream valve must
always be closed first. A bypass line may be necessary to maintain emergency operation.
18.12 Stellited seat and cone
In the case of abrasive media or liquids with pressure drops (inlet pressure minus outlet pressure) of more than
25 bar the valve cone must be stellited; for pressure drops above 150 bar the seat must be stellited as well.
18.13 Leakage line
If toxic or hazardous media are used the valve must feature a sealed spring cap (including setting spindle seal)
fitted with a leakage line connection. When the pressure reducer is installed on site a leakage line must be fitted
capable of safely and pressureless draining the escaping medium in case the control valve should become
defective.
18.14 Mounting position
For gases a back pressure regulator can normally be fitted in horizontal pipelines with the spring cap at the
bottom or at the top. Installation in vertical pipe runs is possible but can result in increased wear and loss of
control accuracy owing to increased friction.
In the case of liquids a back pressure regulator should be installed with the spring cover at the bottom. Thus
gas traps upstream of the valve are avoided which would cause the valve to oscillate.
For steam a back pressure regulator should likewise be installed with its spring cover at the bottom to protect
the diaphragm against overheating by means of a layer of condensate.
In case the valve must be emptied completely during operation (angle valves), it must be installed with the
spring cap pointing upwards.
18.15 Start-up
Back pressure regulators should be started up and operated without pressure surges, if possible. A sudden
operation of upstream or downstream valves should be avoided.
18.16 Steam operation
If a back pressure regulator is installed in a steam plant the diaphragm water reservoir must be filled before the
plant is started up. There must be no danger of overheating at the installation site caused by excessive ambient
temperatures or insufficient heat dissipation. back pressure regulators must not be insolated. In some cases an
insulating of the body is permitted, but only with cast bodies. Never insulate diaphragm housing, mid section
and spring cap (or open springs). Overheating caused by insulating destroys the elastomere of the control unit.
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RP 824-4.X.231 Issue 17.11.2023 www.mankenberg.com