Spirax Sarco LP30, Инструкция по установке и обслуживанию

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IM-P402-44 AB Issue 15 8
3. Installation
Before proceeding with any installation or maintenance
read Section 1, 'Safety information'.
When the probe is to be installed in the boiler, ensure it is positioned at least 1 metre (39")
from any safety valve or steam take-off, as increased localised water levels may occur.
3.1 Deciding on the low alarm levels
In most shell boilers the water will 'swell' when it is firing, such that the actual water level will
be higher than the level shown in the gauge glass. In practice this can be up to 50 mm (2")
in very large boilers reducing to about 10 mm ( ") in smaller ones. We recommend, therefore,
that the second low level alarm should be well above the bottom of the gauge glass when
the boiler is cold, as this will reduce when the boiler is firing. The first low level alarm may be
20 mm ( ¾ ") above second low level alarm (see Figure 3). Wherever possible the boiler
manufacturer should be consulted for advice on the working and alarm water levels.
Boiler cold Boiler firing
Level gauge glass
2nd low
1st low
Fig. 3 Typical low alarm levels
2nd low
1st low
3.2 Protection tube
The probe must be installed in a protection tube when used as a low level alarm in a steam
boiler. The protection tube provides a relatively steady water level, shielding the probe from
the turbulence in the boiler. Two separate protection tubes must be provided, one for the first
low level alarm and one for the second low level alarm. A typical protection tube is shown in
Figure 4. Dimensions and construction may be varied to suit the application, but a tube of at
least 80 mm (3") diameter is recommended.
Flange lagging is recommended, particularly on larger boilers or boilers with a working
pressure over 10 bar g (145 psi g). Do not lag the probe.
Do not cover the vent or drain holes on the body.
Note: When making flanged or screwed joints, ensure that excess jointing compound does
not enter the boiler.