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As below we provide the table of “Inlet/outlet pressure relationship” and “KV value, stroke and pressure adjustment range” to facilitate you to give more specific parameters when determining the product specification, so that the reasonable selection can achieve the ideal use effect.
After-valve pressure regulating valve (Type B), the relationship between the pressure before and after the valve.
A self-operated control valve itself is a regulating system. The valve has a specific pressure drop requirement. For the post-valve regulation type self-operated pressure regulating valve (Type B), the pressure before the valve must reach a specific value to ensure that the pressure after the valve is in a particular range. The requirements can be found in Table 5.
Note: 1. If the valve parameters required by the user are outside the range listed in Table 5, please get in touch with BCST.
- For pressure setpoints ≤ 15Kpa, we recommend conductor-operated self-operated pressure regulating valve or self-operated micro-pressure regulating valve.
Table 5
Pressure before valve（kpa） | Pressure after valve (kpa) | Pressure before valve (kpa) | Pressure after valve (kpa) |
30 | 15-24 | 650 | 65-520 |
50 | 15-40 | 700 | 70-560 |
100 | 15-80 | 750 | 75-600 |
150 | 15-120 | 800 | 80-640 |
200 | 20-160 | 850 | 85-680 |
250 | 25-200 | 900 | 90-720 |
300 | 30-240 | 950 | 95-760 |
350 | 35-280 | 1000 | 100-800 |
400 | 40-320 | 1250 | 125-1000 |
450 | 45-360 | 1500 | 150-1200 |
500 | 50-400 | 2000 | 200-1600 |
550 | 55-440 | 2500 | 250-2000 |
600 | 60-480 | 3000 | 300-2400 |
Table 2 Rated Kv value, rated stroke, pressure adjustment range
| DN(mm) | 20 | 25 | 32 | 40 | 50 | 65 | 80 | 100 | 125 | 150 | 200 | 250 | 300 | |
| Rated flow coefficient Kv | Single seat | 7 | 11 | 20 | 30 | 48 | 75 | 120 | 190 | 300 | 480 | 760 | ＼ | ＼ |
| Sleeve | 7 | 11 | 20 | 30 | 48 | 75 | 120 | 190 | 300 | 480 | 760 | ＼ | ＼ | |
| double seat | ＼ | ＼ | 22 | 33 | 53 | 83 | 132 | 209 | 330 | 528 | 836 | 1210 | 1925 | |
| Rated stroke(mm) | 8 | 10 | 14 | 20 | 25 | 40 | 50 | 60 | 70 | |||||
| Pressure control range（Kpa） | 15-50 40-80 60-100 80-140 120-180 160-220 200-260 240-300 280-350 330-400 380-450 430-500 480-560 540-620 600-700 680-800 780-900 880-1000 950-1100 1080-1250 1230-1400 1380-1550 1530-1800 1780-2000 1980-2300 2280-2500 | |||||||||||||
- From the above two tables, 3 types of self-operated pressure regulating valves are derived, with differences in price.
- If pressure set point ≦15Kpa, it shall use a self-operated pressure regulating valve with commander operation or a self-operated micro-pressure regulating valve.
- If pressure set point between 15 and 800 Kpa, it shalluse”diaphragm” type control valves, i.e. the general self-operated pressure control valves as we quoted.
- If pressure set point > 800 Kpa , it shall use self-regulated control valve with”piston” actuator.
B．Superiority of bellows compared to O-rings.
- Wear resistant, long life and better sealing
- Better adjustment stability
- Steam pipework to be sealed with “bellows” and condensate tanks
Remark:
- Model selection, order should specify the working conditions (including at least the medium, operating temperature, maximum/minimum flow rate before/ after the valve, differential pressure adjustment range)
- The “bellows” seal requires special instructions
- Read the product manual carefully and choose the correct installation method according to the working conditions
