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VDL (E3.1) 10/2020 Page 39/196
To create the connection between the vacuum drying oven and the pump, an antistatic PTFE hose is
used. All conductive parts have the same electrical potential. Also, the door handle is conductive.
Any clothing, shoes and gloves worn by the user shall be ESD protected.
When installed and operated as intended, there will be equipotential bonding for loading and unloading
and there is no risk of charges that are hazardous to operation.
• Extraction
Active extraction (technical ventilation) during operation of the VDL is mandatory.
The extraction has to be provided as technical ventilation according to country-specific regulations
(TRBS 2152 Part 2 for Germany). It must include the entire installation area of the vacuum drying oven
and pump. In normal operation, it affects in particular the loading area of the chamber to limit and reduce
any possible explosive atmosphere when loading the device.
Spreading of an explosive atmosphere to non-protected areas is prevented by the prescribed technical
ventilation.
Fault: If solvents or solvent vapors inadvertently reach areas of the installation location (e.g. if the ma-
terial to be loaded or the filled condensate catchpot of the pump fall down), the chamber must be turned
off immediately (pull the power plug or operate e.g., a customer's explosion-protected emergency stop
switch) in order to prevent explosive atmosphere from penetrating into non-protected areas. The tech-
nical ventilation at the installation site reduces the explosive atmosphere.
If, during a fault of the technical ventilation, material containing a solvent is located in the loading area
of the chamber, it must be removed immediately. If material containing a solvent is located inside the
chamber because it is being loaded at that moment, close the chamber door. The operator must ensure
that no explosive atmosphere remains in the area around the chamber when there is no active technical
ventilation. Ensure that the operator can manually turn off the chamber immediately (pull the power plug
or operate e.g., a customer's explosion-protected emergency stop switch) in order to prevent the cham-
ber from restarting automatically.
If, during a fault of the technical ventilation caused by a power failure, material containing a solvent is
located in the loading area of the chamber, the operator must ensure that after the power has been
restored, the technical ventilation and sweeping the electrical installation area, preheating chamber and
controller housing with maximum overpressure have been active for a defined time (chap. 9.3.2) before
turning on the chamber.
• Sealing
The area for electrical equipment is sealed so far that an overpressure can be built up. In combination
with sweeping with compressed air and the specified technical ventilation (extraction) provided by the
operator, the penetration of solvent vapors into the area for electrical equipment, preheating chamber,
and controller housing is prevented when loading the device as well as when unloading material that
has not completely dried.
• Authorization levels of the chamber controllers with password assignment
This makes it easier to restrict the use to trained users.
• Construction of the pump module and mandatory extraction, requirements for vacuum pumps
Various constructive features and measures to be taken by the operator prevent solvent vapors from
penetrating into the hot pump motor and into the electrical installation area, preheating chamber, and
controller housing (triangular instrument box) of the VDL in the event of incorrect operation, e.g. spilling
the content of the condensate catchpot of the pump when emptying it:
• Installation of the entire system under extraction (technical ventilation), this must run when emptying.
• Use of Ex pumps corresponding to the zoning is mandatory
• An extraction system provided by the customer must be connected to the port of the pump module.
This keeps the concentration in the pump module low
• The condensate collecting tray provided in the pump module prevents leakage
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