172-65627M-09 (SQ10) 18 Oct 2021
8
Temperature Stability
The unit is capable of supplying water with a temperature deviation of
1
C of the
set temperature when there is little fluctuation in the amount of water and the unit is
in stable operation. However, rapid operation of the valve for water supply, or rapid
temperature changes of the supply water, may temporarily result in a temperature
deviation greater than 1
C of the set temperature.
The valve for water supply system should be adjusted as slowly as possible.
For reference, the table below gives examples of possible water temperature
deviations, at a set temperature of 60
C and 0.3 MPaG steam pressure, according
to the relative change of water flow rate and valve operation time.
Example 1 below shows that when reducing the flow rate of the supply water from
2 m
3
/h to 1 m
3
/h (relative change of 50%), even operating the water supply valve
for 30 seconds will result in a temporary water temperature deviation of
3
°
C.
Example 4 shows that when reducing the flow rate of the water supply from 16
m
3
/h to 15 m
3
/h (relative change of 6%), even rapid operation of the water supply
valve will result in a temporary water temperature variation of only
1
°
C.
As the water temperature deviation increases with the relative change of water flow
rate and reciprocal to valve operation time, operate the valve over a period equal to
or longer than the corresponding valve operation time in order to keep the water
temperature deviation equal to or lower than the value shown in the table below.
No.
Water Flow Rate
Change
(m
3
/h)
Relative Change of
Water Flow Rate
(%)
Valve Operation
Time
(seconds)
Water Temperature
Deviation
(
C)
1
2
→
1
50
30
3
2
4
→
3
25
3
3
3
8
→
7
12.5
0.5
1.5
4
16
→
15
6
0.3
1
