Selecting Valve Type And Nominal Diameter; Selecting Rated Pressure And Valve Material; Selecting The Setting Range; Selecting Elastomer Materials - Mankenberg Rp 824 Originalbetriebsanleitung

Original operating manual
pilot-operated pressure regulators RP 824

18.2 Selecting valve type and nominal diameter

Using your maximum operating data and the smallest differential pressure Δp, you should calculate the
characteristic performance figure K
value is 30 % greater than the calculated Kv figure. Additional allowances must be made for high-viscosity
liquids or liquids which vaporise when depressurised. Back pressure regulators should not be overdimensioned.
Their optimum working range is within 10 % to 70 % of their K

18.3 Selecting rated pressure and valve material

The rated pressure must exceed the maximum system pressure, irrespective of safety allowances. Please note
also the effect of the temperature (see DIN 2401).

18.4 Selecting the setting range

For good control accuracy you should select a setting range which places the required inlet pressure near its
upper limit. If, for example, the controlled inlet pressure is to be 2.3 bar, you should select the 0.8 to 2.5 bar
setting range, not 2 to 5 bar. If the available setting range is not wide enough you may go below the bottom limit
of the setting range provided that the valve loading is kept low and a high control accuracy not required.

18.5 Selecting elastomer materials

You should select eleastomers according to the operating temperature and the requirements of the medium.
High-pressure gases, for example, can diffuse into the elastomer and cause damage when being
depressurised.

18.6 Flow velocity

Depending on pressure drop and permitted maximum noise level, we recommend the following flow velocities:
Liquids 1
Saturated steam 10
Superheated 15
steam
Gases below 2 bar 2
Gases above 2 bar 5

18.7 Sense line (control line)

You should install a sense line if the selected back pressure regulator is designed for sense line operation. The
sense line should be connected at a distance of not less than 10 times nominal diameter upstream of the valve.
No isolating valves should be installed in the sense line to avoid an excessive pressure differential between
valve body and diaphragm. To attenuate any oscillations occurring in the pipeline system, the sense line may be
fitted with a restrictor which must never be fully closed during operation.
In the case of steam and liquids the sense line must be installed so as to fall towards the valve. Under special
operating conditions, for example intermittent operation with dry steam, an compensation vessel must be
installed. The sense line must be rigid as elastic hoses can induce oscillations.

18.8 Protecting your system

To protect your system you should install a safety valve upstream of the back pressure regulator to prevent the
maximum permitted operating pressure (normally 1.5 x maximum set pressure) being exceeded. The safety
valve operating pressure should be set approximately 40 % above the maximum set pressure of the back
pressure regulator to avoid blow-off during slight pressure fluctuations.
For example: if the setting range of the back pressure regulator is 2 - 5 bar the safety valve operating pressure
must be 1.4 x 5 bar = 7 bar.
RP 824-4.X.231 Issue 17.11.2023
(see leaflet Calculation of Pressure Regulators). Select a valve whose K
v
- 5 m/s
- 40 m/s
- 60 m/s
- 10 m/s
- 40 m/s
27
value.
vs
vs
www.mankenberg.com