English (GB)
5
English (GB) Installation and operating instructions
Original installation and operating instructions.
CONTENTS
Page
1. Symbols used in this document
2. General information
These installation and operating instructions are a supplement to
installation and operating instructions for NK, NKG pumps.
3. Product description
This type of double seal consists of two shaft seals mounted in a
back-to-back arrangement in a separate seal chamber or of a
cartridge seal.
Fig. 1
Back-to-back seal arrangement consisting of two shaft
seals
The back-to-back seal arrangement is suitable for applications
where leakage of the pumped liquid to the environment is
unacceptable. The back-to-back double seal protects the
surrounding environment and the people working near the pump.
In back-to-back seal arrangements, the pressure in the seal
chamber must be higher than the pumped liquid pressure in order
to prevent the pumped liquid from leaking through the shaft seal
to the environment.
The back-to-back shaft seal arrangement is particularly suitable
for liquids with many abrasive particles. The seal arrangement
prevents the pumped liquid from entering the seal gap and,
consequently, prevents excessive wear. In this case a single-seal
arrangement would either wear out or be damaged.
Pumps with a back-to-back shaft seal arrangement require a
pressurising system providing the correct pressure to the barrier
fluid in the barrier fluid chamber.
4. Applications
The back-to-back double-seal arangement is the optimum
solution in these cases:
•
The pump is pumping toxic and explosive liquids.
•
The pump is pumping aggressive and abrasive liquids.
•
The pump is pumping hardening liquids, e.g. oil products.
•
The pump is pumping sticky liquids, e.g. paint and varnishes.
•
The pump is operating with a negative inlet pressure (vacuum)
of 0.7 - 0.9 bar compared to the pressure in the barrier fluid
chamber.
The back-to-back seal arrangement can handle a pumped liquid
temperature up to 140 °C.
Periods of inactivity and frost protection
10.1 Service kits and service instructions
Warning
Prior to installation, read these installation and
operating instructions. Installation and operation
must comply with local regulations and accepted
codes of good practice.
Warning
If these safety instructions are not observed,
it may result in personal injury!
Caution
If these safety instructions are not observed,
it may result in malfunction or damage to the
equipment!
Note
Notes or instructions that make the job easier
and ensure safe operation.
TM
04
60
58
47
09
Pos.
Description
1
Primary shaft seal
2
Secondary shaft seal
3
Seal chamber, containing barrier fluid
3
1
2
