8 Servicing/Maintenance
33 of 44
Hya-Duo D FL
8.4 Setting the pre-charge pressure
WARNING
Wrong gas
Danger of poisoning!
▷
Use only nitrogen to charge the accumulator.
CAUTION
Pre-charge pressure too high
Damage to the accumulator!
▷
Observe the manufacturer's product literature (see name plate or operating
manual of the accumulator).
The pre-charge pressure of the accumulator (p) must be below the set start-up
pressure (p
E
) of the fire-fighting system.
The best storage volumes are achieved at the following settings (average value):
▪
Factor 0.9 at pre-charge pressure > 3 bar
▪
Factor 0.8 at pre-charge pressure < 3 bar
Example 1
p
E
= 5 bar
5 bar × 0.9 = 4.5 bar
At a start-up pressure of 5 bar the pre-charge pressure of the accumulator must be
set to 4.5 bar.
Example 2
p
E
= 2 bar
2 bar × 0.8 = 1.6 bar
At a start-up pressure of 2 bar the pre-charge pressure of the accumulator must be
set to 1.6 bar.
Checking the pre-charge pressure
1. Close the valve under the accumulator.
2. Drain the accumulator via the drain valve.
3. Remove and store the protective cap of the accumulator valve.
4. Check the pre-charge pressure with a suitable pressure gauge (e.g. tyre pressure
gauge).
5. Fit the protective cap of the accumulator valve.
Filling the accumulator
1. Remove and store the protective cap of the accumulator valve.
2. Re-fill nitrogen through the valve.
3. Fit the protective cap of the accumulator valve.
