5
MT 237 – EN ed.2015 (Rev.A)
The tripping due to pressure decrease instead occurs as follows.
As long as the pressure value
Pd
remains above the calibration load of the spring
546
, the spring support
544
remains leaning on the
support
545
.
If the pressure
Pd
decreases below the pre-set value, the spring
546
makes the support
544
and consequently the shaft
535
move.
Consequently, the cam moves the touch probe
509
causing the release of the lever mechanism.
The restoration of the block occurs by pulling the bushing
531
until the lever mechanism is coupled again.
During the first stage of the manoeuvre, it is necessary to wait until the upstream pressure passes downstream of the obturator - through
the internal bypass - and balances it. After restoring the slamshut valve to its open position, bushing
518
has to be press-fit into its seat.
The opening or closing status of the slam-shut valve is detectable from outside by observing the position of the colored cap
531
through the
plug
532.
1.3
CALIBRATION SPRINGS
Table 1.1 shows the calibration ranges of the different available springs.
FEATURES OF THE SPRINGS FOR LA/BP SLAM-SHUT VALVES
Code
Colour
De
Lo
d
Calibration range (mbar)
Tripping due to maximum pressure
64470112RO
RED
34
43
2.2
30 ÷ 49
64470115GR
GREY
34
42
2.8
50 ÷ 180
Tripping due to minimum pressure
64470024BI
WHITE
15
45
1.3
6 ÷ 60
De = Ø external d = Ø wire Lo = Length
FEATURES OF THE SPRINGS FOR LA/MP SLAM-SHUT VALVES
Code
Colour
De
Lo
d
Calibration range (mbar)
Tripping due to maximum pressure
64470115GR
GREY
34
42
2.8
140 ÷ 179
64470116GI
YELLOW
34
40
3.2
180 ÷ 279
64470051BI
WHITE
34
50
3.2
280 ÷ 450
Tripping due to minimum pressure
64470024BI
WHITE
15
45
1.3
10 ÷ 59
64470038GI
YELLOW
15
40
2
60 ÷ 240
De = Ø external d = Ø wire Lo = Length
FEATURES OF THE SPRINGS FOR LA/TR SLAM-SHUT VALVES
Code
Colour
De
Lo
d
Calibration range (mbar)
Tripping due to maximum pressure
64470116GI
YELLOW
34
40
3.2
250 ÷ 549
64470051BI
WHITE
34
50
3.2
550 ÷ 849
64470057BL
BLUE
34
50
3.5
850 ÷ 1399
64470058AR
ORANGE
34
50
4
1400 ÷ 2499
64470059AZ
LIGHT BLUE
34
50
4.5
2500 ÷ 3999
64470060NE
BLACK
34
48
5
4000 ÷ 5500
Tripping due to minimum pressure
64470038GI
YELLOW
15
40
2
100 ÷ 499
64470045MA
BROWN
15.3
41
2.4
500 ÷ 999
64470046BL
BLUE
15
40
3
1000 ÷ 1999
64470149NE
BLACK
15
43
3.2
2000 ÷ 3500
De = Ø external d = Ø wire Lo = Length
