Ambient valves

A control valve, or regulation valve, serves as an actuator in a control loop. As a throttle device, it enables the desired volume of flow to be set in a pipeline. Control valves from STÖHR ARMATUREN control the flow in a process plant. For this purpose, the valve stem (spindle) is connected to the valve cone. This closes the valve seat ring by resting against the media pressure. When the spindle moves up, the flow opens and increases the flow rate depending on the profile of the control cone. 

Closing the flow narrows the cross-section of the flow. The pressure of the medium decreases, and its flow rate increases. After the cross-sectional constriction, the velocity of the medium returns to around its former value, assuming the pipe diameter before and after the throat is the same, though it is common for a pressure drop ("ΔP") to remain. This can be indicated as a characteristic value. The geometric shape of the cone determines the flow characteristic. This can be carried out in a linear or equal percentage manner, or according to customer-specific requirements. 

Control valves are typically controlled by an automated actuator. Manual control valves may be used, but these are less accurate. Most actuators are pneumatic, but electrical and solenoid actuators are also available. In addition to the pneumatic actuator, a control valve is usually equipped with a position controller (IP controller), and a limit switch may be used as backup. 

A check valve is a valve that opens the flow of the medium in only one direction – the flow direction – and closes against the recirculating flow of media. The medium can be both in gaseous or liquid state. 

In spring-loaded check valves, the shut-off element takes the form of a plate, ball or cone which opens the valve when the media begins to flow in the intended direction, creating a pressure that’s greater than the closing force of the spring. This spring closes the shut-off element when the media pressure falls below the closing pressure of the spring force, or when the medium flows in the opposite direction.

A spring-less check valve – such as the STÖHR Magros Series 1500 – opens its valve plug when the pressure of the media flow is greater than the forces of attraction of the magnet located in the valve housing. As the opening increases, the force needed to open the cone further reduces. Thus, the energy loss at fully open poppet is comparatively lower than that of a spring-loaded check valve. Unlike the spring, the magnet is not subject to material fatigue or wear, and hence magnetically loaded check valves can be described as being maintenance-free. 

An overflow valve is an axially aligned valve in which the medium flows along the direction of construction. The media pressure prevents the closing of the valve by pressing a ball against a spring. As soon as the media pressure falls below the spring force, the valve closes. In the open state – in which the spring tension is less than the media pressure – the medium flows past the ball on the valve seat (overflow). 

A globe valve – often referred to as an open/close valve or shut-off valve – controls the opening and closing of flow openings or medium pipes, and is used to regulate the flow in fluid and gas installations. Globe valves are operated manually using a hand wheel, by a motor, or by an external drive, which can be pneumatic, electric or magnetic. While ball valves are shut off with a hand movement, the flow is continuously throttled by axial rotation of the spindle in stroke valves, while the cross-sectional area of the valve opening is gradually reduced until the shut-off cone rests flat on the valve seat and interrupts the media flow. 

The globe or shut-off valve is intended to achieve both full flow and full shut-off of flow. To achieve shut-off, a shut-off cone rests flat on the valve seat and is pressed against the medium flow. A controlled medium flow is not possible with a shut-off valve. 

In fluid technology, a filter or strainer retains solids from a gas or liquid flow – much like a sieve. The solid-free phase is usually referred to as filtrate in the filtration of liquids, and in gas filtration as pure gas. Filtration is especially important in the gas phase, where gas flows through the valve seat into a filter cartridge and is pushed through the filter meshes. 

The driving force of filtration is the pressure difference that occurs in the transport medium before and after the filter. The medium is pressed through the filter with excess pressure. Once the medium has passed through the filter, a pressure drop ("ΔP") occurs. The smaller the filter mesh, the higher the resulting pressure loss. It may be possible to minimise this loss of pressure by enlarging both the filter housing and the filter insert (also known as the filter cartridge). 

Gas filters consist of a permeable filter mesh made of stainless steel wire of different qualities welded to a steel ring at the top and bottom. The fabric may have different-sized passages, the spacing of which is typically between a minimum of 3μ and a maximum of 100μ – often referred to as mesh size. The standard mesh size for filters from STÖHR ARMATUREN is 40μ. Other mesh sizes are available on request. 

If a filter insert becomes polluted, it can easily be removed from its housing, cleaned with distilled water or nitrogen, and reinstalled. Start by depressurising the pipe, then loosen the screws in the housing on top of the filter and remove the filter cartridge. After cleaning, the filter cartridge can simply be screwed into a thread at the seat, or inserted without threading. See the operating and maintenance manual for full details.

STÖHR ARMATUREN has designed a bellows-driven pneumatic actuator especially for applications with radiation.
This development avoids damage to plastic parts and ensures maintenance-free operation without gas emissions to the environment.

Special feature:

• radiation proof
• maintenance-free
• free of gas emission

Depending on the valve series, our valves can be equipped with a manual drive (handwheel), pneumatic piston actuator, pneumatic diaphragm actuator, electric actuator, hydraulic driven actuator or solenoid actuator. Available combinations can be found in our product catalogue or on this website.

Depending on the requirements of your application, manual override may be required on automated actuators to close the valve in the event of a malfunction, such as power failure or loss of pressure in the pneumatic line. STÖHR ARMATUREN offer manual override as an option for many types of actuators. Please specify your requirements when requesting a quote. 

We use our own pneumatic piston actuator for globe valves of up to size DN 100, and source piston or diaphragm actuators from well-known manufacturers for other applications. The standard operating pressure is 6 bar. 

Our piston actuator can be customised to suit special operating conditions such as non-industry standard operating pressures, stainless steel manufacture for installation in a marine environment, use of radiation-resistant materials, exclusion of non-ferrous metals, or vacuum-tightness to the environment. 

Our valves are available with electric actuators from well-known manufacturers for shut-off. Please specify the required electrical performance parameters (direct or alternating current, voltage, etc) when requesting a quotation.

In addition to actuators using electric motors, valves from STÖHR ARMATUREN can also be equipped with solenoid operated actuators sourced from well-known manufacturers.

We buy diaphragm actuators for control valves from well-known manufacturers. The brands and products we use are listed in our product catalogue or contained in your offer. ATEX-approved types are required for use with flammable media. If you prefer manufacturers or types other than those we offer as standard, please let us know and we will check for alternatives. 

Compressed air is usually used as an operating medium, but nitrogen or intrinsic gas supply may be possible. The standard pressure supply to the pneumatic actuator is 6 bar maximum. If you require another pressure level, please let us know in your quotation request. 

All STÖHR products adhere to the following standards:

• Pressure-bearing parts made of solid material
• Housing and connections made of stainless steel or special steel
• High tightness of the first spindle seal to the outside using a bellows seal
• Additional safety of the second spindle seal using an O-ring or metal ring
• Media-adequate use of materials (steels and seals)
• Fulfillment of the required industry standards according to European regulations
• High operational safety
• Low maintenance and spare parts requirement
• Very low failure rates
• Long lifetime
• Low lifecycle costs

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Our customers experience the following advantages:

• Expert advice and support from true product specialists
• Bespoke products manufactured to your exact specifications 
• Help to define your requirements to suit your project
• Products supplied ready for installation 
• A fast and effective response to any incidents
• Long-term replacement supply

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