Richter LPV/F Series Low-Pressure Safety Valves - Manual (Page 9)

Series LPV-A/F, LPV-D/F
Seite 9
9530-060-en Revision 01
TM 7464 Edition 02/2009
6 Installation
The installation conditions to the AD 2000 Code
A2 (on pressure vessels) and TRD721 are to be
observed. They are major preconditions for the
safe operation of the valve.
Examine valve for in-transit damage, damaged
low-pressure safety valves must not be installed.
Before installation the valve and the connecting
pipe must be carefully cleaned to remove any dirt,
especially hard foreign matter.
Solids jeopardise the soft, plastic, high-precision
sealing surfaces of the seat and plug and
permanent leaks of the valve may occur.
During installation, pay attention to the correct
tightening torque, aligned pipes and tension-free
assembly.
Temperature-related changes in length of the pipes
must be allowed for, e.g. by installing expansion
joints.
Remove flange caps.
Position and align the valve. Then tighten the pipe
screws with a torque wrench in diametrically
opposite sequence.
For tightening torques, see Section 1.4.
6.1 Sizing of the outlet line
The admissible pressure loss in the inlet line must not
exceed 3% of the set pressure of the low-pressure
safety valve.
The determination of the pressure loss relates to the
maximum flow of the valve at 110% of the set
pressure and 110% of the certified coefficient of
discharge.
An excessive pressure loss at the inlet of the low-
pressure safety valve can cause rapid opening and
reseating of the valve or chattering.
Chattering results in a reduction in the discharge
capacity and may cause an inadmissible rise in
pressure in the system and damage to the seat
sealing surfaces.
The inlet line must never be smaller than the
nominal diameter of the safety valve inlet.
Lay supply lines as short as possible.
Install, if at all possible, the valve directly on the
container to be protected.
At least chamfer the container nozzle in the inlet or
even better provide with a radius.
An inlet nozzle with a tapered design has the best
shape in terms of flow.
6.2 Sizing of the outlet line
Outlet lines are to be sized so that reliable
functioning of the valve is ensured under all
expected operating conditions.
The medium is to be discharged so that there is no
risk to people and the environment. The statutory
provisions (e.g. accident prevention regulations, and
the equivalents of the German Pollution Control Act or
the German Clean Air Code) as well as local
regulations (works standards) are to be observed.
There must be no possibility of the safety valves
becoming ineffective due to shut-off elements.
6.2.1 Admissible back pressure
The outlet line must never be smaller than the
nominal diameter of the low-pressure safety
valve outlet.
The max. admissible back pressure is 15% of the
test gauge pressure. It must not be exceeded. A
reduction in the blowdown capacity is thus avoided.
6.2.2 Drainage of condensate
Lay horizontal pipes with a gradient away from the
valve so that the liquid medium cannot accumulate in
the valve body and that, in the case of gases, no
condensate collects in the body.
If outlet lines are laid with a geodetic level difference
(e.g. for vapours or gases with a 90° vertical upright
pipe bend out of the valve), the bend must not be
located directly downstream of the valve.
A horizontal pipe section with a gradient must firstly be
installed downstream of the valve.
A draining facility must be provided at the lowest point
in the pipe. This opening for the drainage of
condensate must be lower than the flow chamber of
the body.
Lines for the drainage of condensate are to have
adequate cross sections. They are to be laid with a
gradient and must ensure safe drainage of the
medium.