Grundfos DMH 28X Installationsanleitung Seite 21

6.7 Pipe lines
6.7.1 General
Warning
To protect the dosing system against excessive
pressure build-up, install a relief valve in the
discharge line.
Only use the prescribed line types!
All lines must be free from strain!
Avoid loops and buckles in the tubes!
Keep the suction line as short as possible to avoid
cavitation!
If necessary, use swept bends instead of elbows.
Observe the chemical manufacturer's safety
instructions when handling chemicals!
Make sure that the pump is suitable for the actual
dosing medium!
The flow must run in the opposite direction to gravity!
The resistance of the parts that come into contact
with the media depends on the media, media
temperature and operating pressure. Ensure that
Caution
parts in contact with the media are chemically
resistant to the dosing medium under operating
conditions!
6.8 Connecting the suction and discharge lines
Warning
All lines must be free from strain!
Only use the prescribed line types!
• Connect the suction line to the suction valve.
– Install the suction line in the tank so that the foot valve
remains 5 to 10 mm above the bottom of the tank or the
possible level of sedimentation.
• Connect the discharge line to the discharge valve.
Connection of DN 20 pipe lines
• Depending on the pipe material and connection, glue the pipe
(PVC), weld it (PP, PVDF or stainless steel) or press it in
(stainless steel).
• Fit the gasket.
• Screw the pipe on the valve using the union nut.
Fig. 17 Connection of DN 20 pipe lines
6.8.1 Connecting the dosing head deaeration
The dosing head is equipped with a deaeration screw (V) and
hose nipple (I). During deaeration, dosing medium leaks from the
hose nipple. This may also happen during normal operation. The
dosing medium should either be collected directly or via a
deaeration line in a suitable container.
Warning
Risk of injuries caused by the dosing medium.
Dosing medium leaks from the hose nipple (I) of the
deaeration line. If the pressure is high, the medium
may squirt out. Turn the hose nipple (I) in the right
direction, or drain the dosing medium through a
suitable hose. Observe chemical resistance!
When using a deaeration line,
• connect the deaeration line (J) to the deaeration screw (V/I).
• Shorten the deaeration line (J) to at least 10 mm above the
maximum tank level.
• Insert the deaeration line (J) downwards into the dosing tank
or collection container without loops. Do not immerse in the
dosing medium.
Fig. 18 Dosing head deaeration
6.8.2 Connecting a liquid-heated dosing head (optional)
As an option, liquid-heated dosing heads are available in
stainless steel.
2f
2f1
40
Fig. 19 Liquid-heated dosing head
Pos. Components
2f Dosing head, liquid-heated
2f1 Hose nipple, DN 10 connection
Required characteristics of heating liquid:
• The heating liquid must not chemically attack stainless steel.
• Maximum permissible pressure: p
• Maximum permissible temperature: t
V
I
J
= 3 bar.
max.
= 100 °C.
max.
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