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Lifting device for maintenance
In the case of safety valves with a lifting device it is recommended, and in certain
plant-specific cases even stipulated that the valves from time to time must be made
to blow-off by lifting the seal off the seat, in order to assure the correct functioning
of the safety valve. They can be opened at an operating pressure of 85 % of the
response pressure at the latest. An examination of the mobility of the safety valves
must take place at intervals of at least 4 weeks in accordance with TRD 601 for
steam generators.
Safety valves represent the last point of protection for the silo or installation. They
should be capable of preventing unauthorized excess pressure when all other
upstream regulation, control and monitoring devices fail. To ensure these functional
characteristics safety valves require regular and recurring maintenance. The main-
tenance intervals shall be determined by the operator according to the operating
conditions and local statutory provisions on site.
When using the valve with foods and other delicate goods, the valve should be
regularly checked (e.g. several times per shift) to see whether it has opened or re-
sponded and the product has flowed out through the valve. In this case, it must be
thoroughly cleaned at the next cleaning interval (see point 6 on cleaning the fitting).
6
Cleaning the fi tting
To guarantee a consistent hygiene status during the whole operating period of the
valve, cleaning and disinfection work must be carried out within specific time inter-
vals. The frequency of the work to be carried out is to be specified by the operator
using the hygiene standards and the sensitivity of the products being processed
as well as the operating and environmental conditions and should be integrated
in the specific cleaning and/or disinfection plan for the company. The fitting is to
be cleaned according to methods typical to the industry and with the necessary
detergents. The resistance of the valve material must be considered when selecting
detergents and disinfectants and coordinated with the manufacturer's factory.
Lifting of the valve in order to clean the CIP or SIP is only possible in the tGEP-
version with pneumatic lifting device.
For this purpose, the safety valve is driven into open position by pressurising the
pneumatic cylinder (fig. a) so that cleaning agent or sterilization steam can flow
around the valve disc. The seat disc seal cannot be cleaned or sterilized when
the valve is closed. In addition to CIP-SIP cleaning, the valve can be partially
disassembled for cleaning purposes. After bringing the valve into a depressurized
state, the valve clamp can be released from the connection point between housing
and spring bonnet (fig. c). Then, the entire upper part of the valve can be removed
from the housing. If the upper part of the valve sits to tight in the housing, it should
be loosened with a screwdriver or another suitable pointed device from the housing
(fig. d).
The valve disc assembly is mounted with a snap seat. For cleaning purposes, it can
be removed from the upper part of the valve by pulling strongly and turning it at the
same time (fig. e).
Assembly and maintenance instructions - 4000
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