Archive for category: Valve

Safety Valve

Safety valve is a valve that acts as a protection of equipment from exploding or damaging and it is mainly installed in pressure vessels such as chemical plants, electric power boilers, and gas storage tanks.
Safety Valve is a type of valve that automatically actuates when the pressure of inlet side of the valve increases to a predetermined pressure, to open the valve disc and discharge the fluid (steam or gas); and when the pressure decreases to the prescribed value, to close the valve disc again. Safety valve is so-called a final safety device which controls the pressure and discharges a certain amount of fluid by itself without any electric power support.
Safety valve support not only the safety of the energy industry but also the safety and security of our life.

Start to Discharge Pressure

The inlet pressure at which the safety valve actually starts to discharge and outflow of an extremely small quantity of fluid (steam or gas) are detected at the outlet. The extremely small quantity means a minimum amount of visually or audibly detectable steam, or a minimum amount of gas that can be detected audibly or by using a soap solution. The outflow does not mean the leakage from the valve seat.

Opening Pressure

The inlet pressure at which the valve disc “Pops.” The opening pressure is also called “popping pressure.” “Popping” is an action of discharging fluid inside the valve due to the sudden rise of the valve disc.

Set Pressure

The opening pressure or start to discharge pressure determined in designing.

Closing Pressure

The inlet pressure fell down to the level at which the valve disc and the valve seat are in contact and the lift becomes zero. It is also called “reseating pressure.”

Blowdown

The difference between opening pressure or start to discharge pressure and closing pressure

Over Pressure

The increasing pressure exceeds the set pressure of the safety valve.

Allowable Over Pressure

The overpressure within the allowable range.

Coefficient of Discharge

The coefficient used to calculate the actual discharge capacity from the theoretical discharge capacity. The coefficient is the ratio between the two capacities, and it counts the frictional resistance.

Certified Derated Coefficient of Discharge

The coefficient of discharge to be applied to calculate the certified capacity.

Flow Rating Pressure

The inlet pressure is taken as the basis for determining the certified capacity of the safety valve, which is the sum of the set pressure and the allowable overpressure.

Back Pressure

The pressures existing at the outlet of the safety valve. There are two types as the following: (a) Accumulated back pressure: The pressure existing at the outlet of a safety valve caused by the resistance of the outlet side when the safety valve has been relieved. (b) Existing back pressure: The pressure which has already been superimposed at the outlet before the safety valve is relieved.

Theoretical Discharge Capacity

The discharge capacity calculated supposing that the fluid is free from friction and its flow rate coefficient is 1, and that the valve discharges the ideal gas of fixed specific heat with isentropic change.

Lift

The amount of travel, in the axial direction of the valve or valve rod, away from the closed position to the opened position during discharge of the safety valve

Safety valves protect steam systems and tanks from excess pressure. As they are often the last link in the safety chain, they must remain operational in all conditions.
Safety valves discharge water vapor, neutral gas, steam, and fluid in the event of excess pressure. As soon as normal operating conditions are restored, they close and do not release any more medium.

Feature

Full bore type

• Flanged
• Cast Iron
• Closed type

Application

• Steam
• Air
• Other non-dangerous fluids

Working pressure

• 0.045 – 1.6 MPa (20-100A) , 0.045 – 1.25 MPa (125A) , 0.045 – 1.0 MPa (150A) , According to PT rating

Max Temperature

• 250 degree C

Body

• Cast Iron

Spring chamber

• Ductile Cast Iron

Valve

• Stainless steel

Valve seat

• Stainless steel

Parker Solenoid Valve

Parker Solenoid Valve is an electro-mechanical device that controls fluid flow. This is achieved by opening or closing one or several orifices in the solenoid valve. The (solenoid) coil is the electrical element that converts an electrical signal into a mechanical force which, in turn, shifts the mobile plunger that opens or closes an orifice (nozzle) by means of its seat disc(s). Solenoid valves are usually constructed from 3 distinct components:

• the body (including the sleeve assembly)
• the coil (or coil housing)
• the housing (or nut/nameplate fixing elements)

These 3 modular components are in many cases interchangeable i.e. a valve body can be used with a number of coil/housing combinations.

1-Direct operated valves

The magnetic force is used directly to open or close the passage of fluid at the plunger sealing. The performance is limited by the available performance of the coil (limits of pressure/orifice size.) The pressure rating of the valve starts from zero bar to the maximum value.

2-Pilot operated valves

In cases where it is necessary to control higher flow/higher pressure, it is necessary to use pilot operated valves. The supply pressure enters the direct-operated “pilot stage” which directs the flow to a “pilot chamber” which, in turn, applies the pilot pressure over a large area (generally a diaphragm or a piston). Therefore, a large force is generated to move the main sealing elements against higher pressure or over a large orifice. One condition of operation is to have a minimum pressure available to shift the valve. In most applications, this presents no particular problems (refer to “Magnalift valves” below). The pressure rating of the valve starts from a minimum value (0.3 or 0.5 bar) up to the maximum value.

3-Magnalift valves

The magnalift valves combine the features of a direct operated and a pilot operated. A mechanical link between the plunger and the diaphragm retainer allows the valve to operate as a direct operated valve at low pressures and as a pilot operated valve at higher pressures. The advantage of this design is that the pressure rating of the valve starts from zero bar to the maximum value. Magnalift valves are specified when the valve controls the emptying/filling of a tank under gravity.

Parker Solenoid Valve Technical information

Actuation

• Direct operated
• Magnalift
• Pilot operated

Body Material

• Brass body
• 303 Stainless steel body

Function

• Normally closed
• Normally open
• Magnetic latch control

Connection

• 1/8
• 1/4
• 3/8
• 1/2
• 1
• 1 1/4
• 1 1/2

Pressure (BAR)

• 4 … 100 Bar

Data Sheet

Valve Positioner Samson Type 3730

A valve Positioner is a device used to increase or decrease the air load pressure driving the actuator until the valve’s stem reaches a “POSITION” balanced to the output SIGNAL from the process variable instrument controller.

Valve positioners are used on controlling valves where accurate and rapid control is required without error or hysteresis.

Positioners are generally mounted on the side-yoke or top casing of the pneumatic actuator for linear sliding stem control valves, and at/near the end-of-shaft for rotary control vales. For either basic design type, “mechanical feedback linkage” connected directly to the valve’s stem provides feedback to the controller. The process controller tells the positioner to “change” position; the feedback linkage reports back to the positioner confirming that a change has occurred and gives a “sense” of the magnitude of the change in position.

Type 3730-0 Electropneumatic Positioner

Application

• Single-acting or double-acting positioner for attachment to pneumatic control valves

Setpoint

• 4 to 20 mA

Travel

• 5.3 to 200 mm

Special features

• Simple attachment to common linear actuators with an interface for SAMSON direct attachment, NAMUR rib, valves with rod-type yokes according to IEC 60534-6 and attachment according to VDI/VDE 3847
• Any desired mounting position of the positioner
• Calibrated travel sensor without gears susceptible to wear
• Analog pneumatic output prevents pulsing in case of leaking actuator
• The fast-reacting analog control loop
• High control accuracy (fine tuning) without the dead band and continuous pneumatic output
• The two-wire system with a small electrical load below 300 Ω for explosion-protected version and version without explosion protection
• Output pressure limitation enabled by DIP switch
• Selectable tight-closing function with fixed switching point
• Low air consumption of approx. 110 ln/h independent of supply and output pressure
• Aluminum housing with IP 66 degree of protection
• Check valve in the exhaust airport
• Resistant to shock and vibrations
• Extended temperature range also for intrinsically safe operation
• Travel range selectable within the rated travel range by
  setting DIP switch
• Zero and span adjusted by potentiometers
• Setpoint range and direction of action adjustable

Type 3730-1 Electropneumatic Positioner

Application

• Single-acting or double-acting positioner for attachment to pneumatic control valves. Self-calibrating, automatic adaptation to valve and actuator.

Setpoint

• 4 to 20 mA

Travels

• 3.75 to 200 mm

Opening angle

• 24 to 100°

Special features

• Simple attachment to all common linear and rotary actuators with an interface for SAMSON direct attachment, NAMUR rib or valves with rod-type yokes according to IEC 60534-6-1, or to rotary actuators according to VDI/ VDE 3845
• Any desired mounting position of the positioner
• Simple single-knob, menu-driven operation
• LCD easy to read in any mounted position due to the selectable reading direction
• Variable, automatic start-up
• Preset parameters – only values deviating from the standard need to be adjusted
• Calibrated travel sensor without gears susceptible to wear
• Permanent storage of all parameters in EEPROM (protected against power failure)
• A two-wire system with a small electrical load of 300 Ω
• The tight-closing function can be activated
• Continuous monitoring of zero point
• Two standard programmable position alarms

 

Type 3730-2 Electropneumatic Positioner

Application

• Single-acting or double-acting positioner for attachment to pneumatic control valves. Self-calibrating, automatic adaptation to valve and actuator.

Setpoint

• 4 to 20 mA

Valve travel

• 3.6 to 300 mm

Opening angle

• 24 to 100°

Special features

• Simple attachment to all common linear and rotary actuators
• Any desired mounting position of the positioner (but not suspended)
• Simple single-knob, menu-driven operation
• LCD easy to read in any mounted position due to the selectable reading direction
• Configurable with a PC over the SSP interface using the TROVIS-VIEW software
• Variable, automatic start-up with four different initialization modes
• Preset parameters – only values deviating from the standard need to be adjusted
• Calibrated travel sensor without gears susceptible to wear
• Sub initialization mode (substitution) allows the positioner to be started up in case of emergency whilst the plant is running without the valve moving through the whole travel range.
• Permanent storage of all parameters in EEPROM (protected against power failure)
• A two-wire system with a small electrical load between 300 and 350 Ω depending on version Adjustable output pressure limitation
• Activatable tight-closing function
• Continuous monitoring of zero point
• Integrated temperature sensor and operating hours counter
• Two standard programmable position alarms
• Self-diagnostics; alarms as condensed state conforming to NAMUR Recommendation NE 107, issued over a fault alarm contact or optional analog position transmitter
• Integrated EXPERTplus diagnostics for control valves

Type 3730-3 Electropneumatic Positioner with HART communication

Application

• Single-acting or double-acting positioner for attachment to pneumatic control valves. Self-calibrating, automatic adaptation to valve and actuator.

Setpoint

• 4 to 20 mA

Valve travel

• 3.6 to 300 mm

Opening angle

• 24 to 100°

Special features

• Simple attachment to all common linear and rotary actuators
• Any desired mounting position of the positioner (but not suspended)
• Simple single-knob, menu-driven operation
• LCD easy to read in any mounted position due to the selectable reading direction
• Configurable with a PC over the SSP interface using the TROVIS-VIEW software
• Variable, automatic start-up with four different initialization modes
• Preset parameters – only values deviating from the standard need to be adjusted
• Calibrated travel sensor without gears susceptible to wear
• Sub initialization mode (substitution) allows the positioner to be started up in case of emergency whilst the plant is running without the valve moving through the whole travel range.
• Permanent storage of all parameters in EEPROM (protected against power failure)
• A two-wire system with a small electrical load of 410 Ω
• Adjustable output pressure limitation
• Activatable tight-closing function
• Continuous monitoring of zero point
• Integrated temperature sensor and operating hours counter
• Two standard programmable position alarms
• Self-diagnostics; alarms as condensed state conforming to NAMUR Recommendation NE 107, issued over a fault alarm contact or optional analog position transmitter
• Integrated EXPERTplus diagnostics for control valves

Type 3730-4 Electropneumatic Positioner with PROFIBUS-PA communication

Application

• Positioners for attachment to pneumatic control valves

Valve travel

• from 3.6 to 300 mm ·

Opening angle

• 24 to 100°

Special features

• PROFIBUS-PA Profile 3.01 certified positioner fulfilling all compulsory requirements of PROFIBUS-PA Profile 3.02
• Automatic ID adaptation according to PROFIBUS-PA Profile 3.02 to facilitate the replacement of positioners with Profile 2.0 or 3.0 (e.g. Type 3785)
• Classified status alarms acc. to NAMUR Recommendation NE 107
• DTM file available to integrate the positioner into FDT/ DTM in compliance with specification 1.2
• Simple attachment to all common linear and rotary actuators
• Any desired mounting position of the positioner (but not suspended)
• Single-knob, menu-driven operation
• Automatic start-up
• LCD easy to read in any mounted position due to the selectable reading direction
• Integrated EXPERTplus diagnostics for control valves
• Online changing of control parameters
• Automatic zero monitoring
• Calibrated travel sensor without gears susceptible to wear
• Permanent storage of all parameters (protected against power failure)
• Negligible influence of temperature and supply air
• Adjustable output pressure limitation
• Activatable tight-closing function
• Binary input for DC voltage signals

Limit Switch

A Limit Switch is an electrical contact that is closed (or opened in some cases) by a variety of mechanical attachments (rollers, “whiskers”, levers, etc.) typically used as an input to a control system (relays, PLCs, etc.) to indicate the presence or absence of a physical object. Non-contact sensors like optical or metallic proximity switches are also sometimes called limit switches.

Presence Sensing is the act of detecting the presence or absence of an object with a contact or non-contact sensing device. The sensors then produce an electrical output signal that can be used to control equipment or processes.

Mechanical limit switches are contacted sensing devices widely used for detecting the presence or position of objects in industrial applications. The term limit switch is derived from the operation of the device itself. As an object (or target) makes contact with the operator of the switch, it eventually moves the actuator to the “limit” where the electrical contacts change state.

Through this mechanical action, electrical contacts are either opened (in a normally closed circuit) or closed (in a normally open circuit). Inductive proximity, capacitive proximity, and photoelectric sensors perform this same process through non-contact sensing.

Limit Switches Application

A limit switch is an electro-mechanical device that consists of an actuator mechanically linked to a set of contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection. Limit switches are used in a variety of applications and environments because of their ruggedness, simple visible operations, ease of installation and operational reliability.

Limit switches are used in an assortment of applications and environments due to their ruggedness, simplicity of installation and reliability of operation.

They are available in a variety of body, rotary arm styles, operation requirements, and environmental factors including moisture, contamination, temperature, shock, and vibration. Other factors to consider when selecting a limit switch include operating force, reset force, over-travel, pre-travel, along with safety requirements. Limit switches are also available in four unique categories: Global, Medium-duty, Heavy-duty, and Safety Locking an Unlocking Styles.

Some application of limit switches:

• Material handling – packaging, moving, warehousing, distribution
• Working where people cannot. Inside a sawmill, a high-speed saw quickly reduces logs into construction beams.
• Food & beverage packaging, distribution
• Fire safety
• Manufacturing – automotive/heavy equipment, machining, marine/aviation, glass & plastics
• Metals – mining, refining, processing, forming
• Commercial applications
• Control cabinets
• Heavy Conveyors
• Metal processing
• Gates, Doors, Hinges
• Control cabinet doors
• Indoor & outdoor environments

Mechanical limit switch operators are available in many shapes and sizes based on their functionality and application. Switches can be divided into two types: momentary and maintained. Momentary, or “spring return” switches return to their normal state as soon as the actuator is released from the object it is sensing. Maintained switches will remain in the actuated position even after the actuator has been released.

Valve Manifold

The Valve Manifold used to protect the DP transmitter and pressure gauge from a higher range. This device isolates the transmitter from fluid pressure for calibration and for maintenance purposes.

The manifold is a combination of valves in a single body. Each valve will have separate openings ad controls. The manifolds commonly use the ball, bleed, needle, and vent valves.

3-valve manifold

The 3-valve manifold consists of two shut-off valves and one pressure compensating valve. The shut-off valves separate the process from the differential pressure measuring instrument. The pressure compensating valve enables the compensation between ⊕ side and ⊖ side to avoid one-sided overpressure during commissioning and operation.

5-valve manifold

Compared to the 3-valve manifold, the 5-valve manifolds equipped with two additional vent valves. One vent valve per pressure side allows operators the targeted venting of one or both pressure sides of the measuring arrangement.

Through the non-rotating spindle tip, the wear of the sealing elements is reduced. This results, particularly with frequent opening and closing, in a noticeable increase in the service life of the valve manifold.

Advantages of a manifold valve

Manifold valves are used in a number of different applications, ranging from mobile machinery to heavy industrial equipment.

When included in fluid control and/or regulation system, valve manifolds have shown to improve efficiency as well as reduce energy costs. Other advantages include:

• Shorter path flows which reduces pressure drop and heat fluctuations, improving the overall energy efficiency of the system
• Reduction in installation costs as well as fluid connections because of a simpler, more compact design
• Minimum chances of oil leak due to less number of connections, further reducing the need for upkeep against fatigue, wear and  lose joints
• Improved layout due to fewer hoses and connections
• Small, compact cartridge sizes which suits confined spaces

Applications

• Shut off and vent pressure measuring instruments
• For gaseous and liquid aggressive media that are not highly viscous or crystallizing, also in aggressive environments
• Process industry: Oil & gas, petrochemical, chemical industries, power generation, water, and wastewater