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Recommanded flow velocities for liquids

1.segment ball globe eccntric rotary plug: *Inlet velocity <= 10m/s continuous duty service, *Inlet velocity <=12m/s for infrequent duty

2.butterfly: *inlet velocity <=7m/s for continuous duty *inlet velocity <=8.5m/s for infrequent duty

3.Vsonic = 91.2 * SQRT(rT/M) r : specify heat T:temperature (K) M: moler mass

other kinetic energy equtions

1 . Vo=W/(M1PoAo) —->throttling velocity unit m/s
Ao—->valve throttling area :m2
M1=1
W—>Kg/s
Po—>kg/m3

2. KE = Po*Vo*Vo/(2*M) <Kpa> M=1000 Po: kg/m3 Vo:m/s

3. KE = Pc*C/(2*M) For gas and steam ,the fluid velocity at the trim outlet may be sonic.if it is the density of the fluid at the trim outlet must be higher than the outlet desity. in order to pass the given mass flow rate.This higher density can be estimated using Equation 1. by substituting the fluid’s sonic velocity for the outlet velocity and solving for density.then this density and sonic velocity are used in equation 2 to find the kinetic energy.

Velocity criteria for liquids are much lower than forgases because liquid densities are much higher,resulting in higher energy levels.while the velocity limits are quite different,the kinetic energy limits are very close to the same.

fluid velocity requirements,base on the vapor pressure of the fluid (at design temperature) is governed by the following equation: V=SQRT(1000*(P2-Pv)/p) v:m/s P2,Pv : Kpa p : kg/m3

COEFFICIENT = 0.0509*trim throtting area(mm2)/SQRT(flow path resistance coefficient)

the outlet density can be estimate form eqution: outlet density=previous density*outlet pressure/prev pressure.

Pressure Reducing Valve without pressure balancing

Design and principle of operation : The medium flows through the valve in the direction indicated by the arrow. The position of the plug (3) determines the cross-sectional area of flow between the plug and the seat (2). In the pressureless state (control line not connected and no pressure applied) the valve is opened by the force of the set point springs (7). The downstream pressure p2 to be controlled is tapped downstream of the regulator and transmitted over an external control line to the control line connection (9) on the actuator housing (6) where it is converted into a positioning force by the diaphragm plate with operating diaphragm (5). This force is used to move the plug stem (4) and the valve plug depending on the force of the set point springs. The spring force can be adjusted at the set point adjuster (8). When the force resulting from the downstream pressure p2 rises above the spring force adjusted at the set point springs, the valve closes proportionally to the change in pressure. In the version with pressure balancing, the forces produced by the upstream and downstream pressures acting on the plug are eliminated by the balancing diaphragm (10). The plug is fully balanced. The following components of the regulators interact to regulate the pressure of the inert gas.
The input pressure regulator (3) is delivered ready-adjusted. It reduces the upstream pressure p1 to the input pressure pe for the pilot valve (2) to approx. 1 bar (15 psi), ensuring precise pressure control even at varying upstream pressures. The pilot valve governs the control pressure pS for the main valve (1) and corrects the set point pset point. The needle valve (4) is delivered ready-adjusted and lead-sealed. If the pressure in the tank drops slightly below the set point pressure (e.g. due to the product being withdrawn from the tank), the pilot valve (2) is opened by the preloaded set point spring (2.1). As a result, the control pressure pS acting on the actuator diaphragm (1.3) of the main valve (1) increases. The main valve opens, causing the inert gas to flow into the tank until the inert gas blanket is re-established or the set point pressure is reached again. When the pressure in the tank increases constantly , the pressure in the actuator chamber of the pilot valve and main valve increases. The pilot valve (2) closes when the pressure increases above the pressure set point pset point. The control pressure pS does not have any effect in this case. The main valve is closed by the actuator springs (1.1) and the increased inert gas pressure p2. The minimum required differential pressure ∆pmin at the regulator to allow it to function properly is 1 bar (15 psi).

Design and principle of operation

The following components of the regulators interact to regulate the pressure of the inert gas.
The input pressure regulator (3) is delivered ready-adjusted. It reduces the upstream pressure p1 to the input pressure pe for the pilot valve (2) to approx. 1 bar (15 psi), ensuring precise pressure control even at varying upstream pressures. The pilot valve governs the control pressure pS for the main valve (1) and corrects the set point pset point. The needle valve (4) is delivered ready-adjusted and lead-sealed. If the pressure in the tank drops slightly below the set point pressure (e.g. due to the product being withdrawn from the tank), the pilot valve (2) is opened by the preloaded set point spring (2.1). As a result, the control pressure pS acting on the actuator diaphragm (1.3) of the main valve (1) increases. The main valve opens, causing the inert gas to flow into the tank until the inert gas blanket is re-established or the set point pressure is reached again. When the pressure in the tank increases constantly (e.g. during filling), the pressure in the actuator chamber (1.2/2.2) of the pilot valve and main valve increases. The pilot valve (2) closes when the pressure increases above the pressure set point pset point. The control pressure pS does not have any effect in this case. The main valve is closed by the actuator springs (1.1) and the increased inert gas pressure p2. The minimum required differential pressure ∆pmin at the regulator to allow it to function properly is 1 bar (15 psi).

Fluid in the valve reaches its maximum velocity

Fluid in the valve reaches its maximum velocity just slightly downstream of the valve trim’s vena contracta or minimum flowing area. These high velocities produce cavitation, erosion and abrasion which can quickly destroy the valve. Even before damaging the valve, you’ll notice excessive noise, severe vibration, poor process control and product degradation in some fluids.

Density,specific volume and specific gravity

The density of a substance is its mass per unit volume. the coherent SI unit of density is the kilogram per cubic meter(kg/m3) and the symbol designation used in this paper is p(Rho). Other commonly used metric units are: gram per cubic centimeter(g/cm3) or gram per millilitre(g/ml) 1g/cm3= 1 g/ml = 1000kg/m3

the coherent SI unit of specific volume V,which is the reciprocal of density,is the cubic metre per kilogram(m3/kg)

General safety instructions

− The regulator is to be mounted, started up or serviced by fully trained and
qualified personnel only; the accepted industry codes and practices are to
be observed. Make sure employees or third persons are not exposed to any
danger.
− All safety instructions and warnings given in these mounting and operating
instructions, particularly those concerning installation, start-up, and maintenance, must be strictly observed.
− According to these mounting and operating instructions, trained personnel
refers to individuals who are able to judge the work they are assigned to
and recognize possible dangers due to their specialized training, their
knowledge and experience as well as their knowledge of the applicable
standards.
− The regulators comply with the requirements of the European Pressure Equipment Directive 2014/68/EU. The EU declaration of conformity issued for a
regulator bearing the CE marking includes information on the applied conformity assessment procedure. This declaration of conformity can be provided on request.
− To ensure appropriate use, only use the regulator in applications where the
operating pressure and temperatures do not exceed the specifications used
for sizing the regulator at the ordering stage.
− The manufacturer does not assume any responsibility for damage caused by
external forces or any other external factors.
− Any hazards that could be caused in the regulator by the process medium,
operating pressure or by moving parts are to be prevented by taking appropriate precautions.
− Proper transport, storage, installation, operation, and maintenance are assumed.

Self-Operated micro-pressure Control Valve

Self-Operated micro-pressure control valve, which used to upstream pressure lower than 1.4Mpa and operate temperature lower than 120 degree, adjust pressure range is 0.14 to 7.2Kpa, the flow non-corrosive gases . Installation and adjust convenient, easy maintenance
Set pressure range 14 to 720mm H2o High sensitivity, high precision

nirogen seal control valve has two kinds of Nitrogen supply regulation and nitrogen release regulation, which can depend on the pressure change of the regulated medium itself to achieve the purpose of automatic regulation and stable pressure is mainly used to keep the container at the top of the shielding gas (usually nitrogen) pressure constant, so as to avoid directe contact with the air container material, prevent evaporation materials, oxidation, and the safety of vessel; This series of nitrogen sealing device is especially suitable for the gas seal of the vessel. This series of nitrogen sealing device is especially suitable for the gas seal protection system of all kinds of large storage tanks. It can be divided into two tupes: niteogenrelief type(K type )and nitrogen supply type(B type)

Control Valve Noise Summary

The requirement for noise control is a function of legislation to protect our wellbeing and to prevent physical damage to control valves and piping. Noise prediction is a well defined science. Actual results will be within 5 dBA of predicted levels.
Prediction is based upon contributions for:

1. Pressure drop
2.Flow rate
3.P/P1 and trim style
4.Piping and insulation
5.Downstream pressure

Noise reduction is accomplished in two general ways:
1. Source treatment, which acts upon the amount of noise generated.

Noise reduction is accomplished in two general ways:
1. Source treatment, which acts upon the amount of noise generated.
2. Path treatment, which blocks transmission on noise to the environment.

There are two common source treatments:

1. Valve noise trim is based on principles of dividing the flow to create many small noise
sources which combine to a lower level than a single large flow noise. Diffusers used with control valves share pressure drop creating two lower noise sources which again combine to an overall lower level.
2. Path treatment involves use of insulation or absorptive devices to lower the sound level which reaches observers.
Hydrodynamic noise from liquid flow streams can mainly be traced to cavitation. In this case,
damage from the cavitation is of more concern than the noise. Appropriate treatment of the
cavitation source should be initiated through staging the pressure drop.
Two-phase, or pure flashing, applications do not create noise problems, and there is no technically appropriate two-phase noise prediction method