Answer / instru

Rotary valves like Ball, butterfly valves are called as
high recovery valves. High recovery means less pressure drop
ofcourse compare to Globe valves. The biggest problem with
high recovery valves is that they are prone to Cavitation.
In case of Globe valves the path is quite torturous and
hence less prone to cavitation. In case of ball valves flow
is starigh through the ball. Cavitation occurs when pressure
at the vena contract drops below the liquid vapour presure.
In case of ball valves the vena contracta pressure and inlet
pressure have marginal difference ( thats why high
recovery). When inlet pressure and vena contract pressure
are clsoe to each other valve is definetely to cavitate .
Hence Ball valves are not used in applications where
cavitation is likely to occur.

When cryogenic control valve will be applied?

1 Answers  

---

Why mixer nd grinder Is example of constant torque load not variable torque load ???

0 Answers  

---

what is the difference between plant earth and instrument earth? and what type of cable( cable size ) used for both? and why ?

0 Answers  

---

Calculate the maximum pressure drop that can be allowed to occur across a control valve, so that we can prevent cavitation / flashing from occurring. Use the following formula: Δ P allow = Km (P1 – PvapourA) where, Δ P allow - the maximum allowable differential pressure for sizing purposes, or terminal pressure drop; Km- the valve recovery coefficient from the manufacturer’s catalogue; P1 - absolute inlet fluid pressure; PvapourA - absolute fluid vapour pressure at the inlet temperature; Use Atmospheric pressure = 101.3 kPa, P1 = 1200 kPa(g), PvapourA = 4 kPa, KM = 0.72

0 Answers  

---

how to overhaul control valves.what are the proper procedures.

1 Answers   Jindal, QAFCO,

---

why we use -ve voltage in vibration monitoring system.generally we use 4 to 20 mA as output of instrument then why we use voltage in vibration

2 Answers  

---

why flow transmitter showing 2.2ma?

2 Answers  

---

what is droop mode n frequency mode in wood ward governor?

1 Answers   TATA,

---

what is field bus system. need defination

3 Answers   Takreer,

---

how do u calibrate the vacuum transmitter if it shows more reading

0 Answers  

---

Difference between guide wave radar & non guide wave radar ?

1 Answers   UPL,

---

HOW DPT WORKS?

6 Answers   Essar,

---