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Diaphragm Valves vs Electrically Actuated Control Valves

May 23rd, 2019 by

What are Diaphragm Valves?

 

Diaphragm valves are named after a flexible disc that is connected with a platform at the top of the valve body, which in turn, forms a seal. A diaphragm is an adaptable component that responds to pressure and engages a force to open, close and control a valve.

 

Diaphragm valves use a durable diaphragm that is connected to the compressor by a stud, which is proceeded by being shaped into the diaphragm. The diaphragm is shoved, making contact with the bottom of the valve body, to shut-off as an alternative, instead of tweaking the liner closed to shut it off. Diaphragm valves are manually operated and are ideal to control the flow control by offering a variable and precise opening for handling pressure drop through the valve. A handwheel is turned until the desired amount of medium flow is transmitted throughout the system. The handwheel is in motion until the compressor pushes the diaphragm to counter the bottom of the valve body to either halt the flow or make way in the bottom until there is a passage for flow.

 

The diaphragm is secured to a compressor by a stud constructed inside the apparatus. The valve stem is moved up to start or enhance the flow in the compressor. To stop or reduce the flow, the compressor is modulated along with the diaphragm being thrust against the foot of the valves. Diaphragm valves are reliable for managing the flow of liquids containing solid matter and have the ability to be fixed in any position.

 

 

What are Electrically Actuated Control Valves?

 

There are two types of electric valve actuators; rotary and linear. Each of them uses special valves to function.

 

The motor varies in voltage and puts a lot of emphasis on torque generation. To avoid heat damage from excessive functions or override current draw, electric actuator motors come along with a sensor which marks an increase in temperature in the motor mechanisms. The sensor gives out a signal when the circuit needs to be opened when overheated. The circuit can be closed again when the motor reaches a moderate temperature.

 

Electric actuators are dependent on a gear train attached directly to the motor to boost the motor speed which navigates the speed of the device. You can change the output speed by installing a cycle length control variable.

 

 

Why are Electrically Actuated Control Valves better?

 

– You do not need an air supply. Air supply may not be available in many places and it is also hard to keep track on.

 

– Colder climates can cause compressed air systems to freeze or clog but the electrically actuated controlled valves have the ability to withstand these temperatures.

 

– They are cost effective.

   

THE IMPORTANT FEATURES AND ROLES OF A ROLLING DIAPHRAGM

March 14th, 2019 by

Diaphragm seals are found in industries that need maximum execution in severe environments, such as the automobile, aviation, pharmaceutical, and food and water-processing industries. Mechanical systems usually use hydraulic actuators which is one of the major factors in the applications. Rolling diaphragms are ductile fluid control tools that are used to secure a perfect seal in any system, involving a piston and cylinder. Made from a combination of elastomer and fabric, they are found inevery shape and size.

 

The bellofram rolling diaphragm is a pliable and durable seal that has a unique layout which allows proportionately long piston strokes while avoiding the sliding friction, throughout. Coming in the shape of a cone that has been cut, or top hat, the diaphragm is folded within itself when positioned so that, during the mechanism, it rolls and rotates repeatedly on the piston skirt and cylinder wall.

 

The rolling action is easy and trouble-free, completely omitting any sliding contact and diverging friction. The exterior flange is clamped to the cylinder in the middle, connected to the top of the piston, this shapes a faultless blockade, averting pressure loss and massive leakage. It all comes down on the substance and outline that has been chosen to function thoroughly with an applied pressure of 3000 pounds. The temperatures range from –120ºF to +600ºF. There are diaphragms that are accessible, with a high tolerance to oil, acids, alkalies, steam and other corrosive fluids.

 

Features of a Rolling Diaphragm

A couple of advantages of rolling diaphragms include precise, repeatable positioning, long stroke lengths, without a spring rate, that refers to pressure made by rubber trying to return to its moulded area.

 

– It is completely friction free.

– There is no breakaway friction or evasion to start the motion all over again, even after being in one position for a long time.

– The spring rate is constant and there is stability in the resistance that is applied for pressure throughout the stroke .

– Because of its high sensitivity, the diaphragm is easily responsiviations in pressure.

– There won’t be any leaks.

– It is so versatile that it can be equipped for a variety of pressures, temperatures, and liquids.

– The position is consistent along with pressures that are similar, despite the direction of the stroke.

 

Role of Diaphragms in Automotive

Air cylinders have piston and rod seal friction which can encounter a jerk at low speeds or pressures. These seals have low durability, which makes it harder to maintain a course without drift. These can be avoided by replacing them with rolling-diaphragm air cylinders, which don’t have dynamic seals that result in wear and tear, friction or leakage. Furthermore, a top-notch seal is attached around the piston that is held back from the sliding motion and in turn, gives a better seal that doesn’t leak and drain the actuator.

   

What Makes Cryogenic Deflashing Method a Cut Above The Rest?

November 16th, 2018 by

Before the final inspection and packing, moulded rubber parts must undergo a finishing process to remove excess flashes. “FLASH” is an excess amount of rubber that oozes out between the two halves of a mould during the moulding of rubber parts.

 

The flash occurs in areas where different sections of the mould join together and are called the ‘parting line flash’. The remaining part of the mould flash traces around where the different sections of the mould join together.

 

Flashes cannot be avoided no matter what technique has been used to manufacture these rubber products. While manufacturing high-performance materials for growing markets like electronics and automotive, intricate finishes, consistency and strict tolerance must be met.

 

Importance of Cryogenic Deflashing

 

 

This is the only method that makes it possible to eradicate complex flash at the inner dimensions. Parts with a thin flash can be removed through cryogenic deflashing quickly. The traditional deflashing methods generally deliver a poor deflashing effect as it is done manually with the help of blades, scissors or knives. The manual trimming method has a high variability in quality and the production rate due to the geometry of the parts. Since the finish quality is not up to the mark, it leads to high rejection rates. Unevenly deflashed products when used can affect and damage the machine it is used in.

 

The Process of Cryogenic Deflashing

 

 

Cryogenic Deflashing is a combination of rapid rotation, nitrogen and plastic blast media is used to get rid of the flash in an extremely precise and economical way. The rubber parts are arranged in a perforated container which is then inserted in a blast enclosure.

 

The containers rotate and evenly expose all sides towards the blast media. The enclosure is insulated with firm polyurethane foam for stable temperatures. The liquid nitrogen decreases the temperature inside and freezes the flashing to make it fragile.

 

With the use of pure nitrogen with zero moisture the requirement of a dryer is eliminated. A fast-moving impeller shoots the polycarbonate pellets in the container. These high-speed pellets trim the inner as well as the outer diameter flashing neatly in a single operation. The effective lubricity and hardness lessens the impeller’s wear and increases its durability.

 

Parting- line flash thickness determines the capability of the system to finish the moulded part in concurrence with the cycle time and LIN consumption. A thicker flash is more difficult to get rid of and requires lengthier deflash cycle time which results in higher LIN consumption. The optimum parting-line flash thickness is 0.001” to 0.005”. Optimum finish quality and LIN consumption are based on the mould design and condition.

 

 

Advantages of Cryogenic Deflashing

 

 

Cryogenic deflashing offers numerous advantages over other traditional or manual deflashing methods:

 

● This process maintains an element of integrity and precision and ensures greater productivity.

● Due to this using a batch process, the cost of per piece is lesser as the number of parts processed in a specific time increases. This makes the manufacturing process economical and cost-efficient.

● Repairing or replacing a mould rises up the expenses bracket. In this method, the moulds can bede-flashed which extends their durability.

● It delivers consistent results in every lot.

● This technique is completely non-abrasive.

● The entire procedure is highly automated which eliminates the need of a human operator.

● This method eradicates the use of any toxic chemicals and is enclosed to a minimum sound which proves it to be environmental-friendly.

 

Harkesh Rubber uses cryogenic deflashing which is the most advanced deflashing process, unlike most of the other OEM’s. This method polishes the parts (typically O-Rings) and minimizes any sign of the flash or parting line delivering an efficient and precise product.

 

With this process, we ensure precision and fulfill our commitment of delivering a quality product. This technique not only improves the performance of the product but also saves the time and effort invested which eventually reduces the cost of production as well.

   

Valve World Expo: The Biggest Valve Industry Affair Under One Roof!

August 1st, 2018 by

The Valve World Expo is the biggest ground to showcase and encounter the experts from the valve industries around the world. It is a one-stop shop that will assemble many great minds and act as a platform to meet proficient valve industrialists who will display their products at a large scale. It is a substantial interactive platform that focuses on individual communication. Valve World Expo brings together valve expertise from the:

 

● Oil, Gas, Petrochemical, and Chemical Industry

● Food Processing Industry

● Marine and Offshore Industry

● Water and Waste Water Management Industry

● Automotive and Machine Construction Industry

● Pharmaceutical Industry

● Power Generation Industry

 

The Valve World Expo is undoubtedly the most prestigious event for anyone who uses valve technology in their business.

 

Harkesh Rubber has been serving the valve needs for all kinds of engineering industries for the past 35 years. Our services employ a combination of well-established product mastery and ingenious engineering. What makes us idiosyncratic are the custom-made solutions we provide with optimum quality service.

 

We, at Harkesh Rubber, are experienced at fulfilling the technical merchandise requirements for multiple industries within strict timelines. With a reputation for excellence around the world, we have served clients in Asia, Europe, the Middle East, the USA and many other countries.

 

We provide expert solutions for:

 

Rubber Diaphragms

 

The Rubber Diaphragm is a multifaceted tool that is used as a sealing agent between two elements. It has a huge demand in industries like power generation, aerospace, chemical and process, and more.

 

O-Rings

 

O-Rings have a variety of purposes in different application areas. They are used to stop the air from passing between the two ends. They are available in various metric and inch standard sizes. O-Rings are commonly used for plumbing purposes, automobile requirements, air-conditioning technology, and more.

 

Seals

 

The seal is used in rotary shaft equipment to keep dust, dirt, oil or any other contaminants out while keeping it lubricated. The sealing element, the metal case, and the spring are what form the oil seal.

 

Gaskets

 

We are well-renowned for the production of custom-made rubber gaskets. They are used to prevent leakage between two articles under compression. These gaskets are made to withstand and handle extreme pressure and wear.

 

Harkesh Rubber is proud to exhibit at Valve World Expo 2018. The event will be held from the 27th-29th November 2018 in Düsseldorf, Germany. Make sure to visit our booth, located at Hall 4 / F22 at the venue!

   

5 Factors to Consider While Selecting a Pneumatic Diaphragm Actuator

July 27th, 2018 by

Whether it is refineries, manufacturing plants, or pipeline compressor stations, you will find pneumatic diaphragm actuators working day-in and day-out to help run these facilities. An actuator is a mechanical or electromechanical device that converts energy to provide controlled or limited movements.

 

In order to operate, pneumatic diaphragm actuators contain a piston enclosed within a cylinder. They are powered by the external air or gas source to move the cylinder so that they can:

 

● Fully open or close the valve

● Partially regulate the open and close movement

 

Many industries rely on pneumatic actuators for their application. Hence, while choosing one, there are many factors that need to be taken into consideration. Below listed are some of those factors:

 

1. Usage Factors

 

Usage factors play a significant role in the selection of a pneumatic diaphragm actuator. These factors are:

 

Compatibility

Pneumatic diaphragm actuators need an air supply between the range of 40 to 120 psi to produce the necessary torque. However, higher pressures can be difficult to achieve in certain scenarios. At the same time, if your setup can only provide a low pressure, you will need a diaphragm or piston that has a larger diameter.

 

Hence, you will need to select an actuator that can deliver the torque you require despite the pressure limitations that you may face.

 

● Temperature Range

Based on the industry, the working temperatures can vary greatly. Depending on the pneumatic diaphragm actuator and the seals, grease, and bearings used, the operating temperature can range from -40 to 250°F. Depending on your temperature range requirements, you will need to select an actuator that can operate in that range.

 

Hazardous Areas

Pneumatic diaphragm actuators are the preferred choice when it comes to hazardous or toxic environments. This is because they are explosion-proof in nature. However, if there is a lack of compressed air, your best bet is an electric actuator.

 

2. Sizing and Force

 

For a pneumatic diaphragm actuator, the force refers to the amount of torque required to move the valve from its open to closed position. The force required depends on factors like:

 

● Type of the actuator

● Valve torque

● Minimum and maximum supply pressure

● Fail mode

 

What’s more, the size and design of the valve as well as the differential pressure are also taken into consideration. Some of the other factors that the size depends on are:

 

● Media temperature

● Stem packing friction

 

Mechanical characteristics of the valve and the valve system.

 

Since sizing valve actuators is a complex process, it is recommended that trained experts determine this value. If you select an oversized valve actuator, it can damage the stem of the valve. Moreover, these will cost more and amount to wasteful spending.

 

On the other hand, an undersized actuator won’t be able to operate the valve on demand. This becomes an especially crucial factor in case of emergency shutdown valves.

 

3. Frequency of Movement

 

The frequency of movement or operation affects the mechanical drive durability as well as the robustness of the controller. As a result, valves that operate at an infrequent rate (like isolating or regulating duty valves) cause less wear and tear on the mechanical components and controls. Hence, vales that work continuously (like modulating process valves) need more durability in terms of valves used and the pneumatic diaphragm actuator assembly.

 

The capability of pneumatic diaphragm actuators is defined by the number of starts per hour. So, while selecting a valve as per the duty cycle look for:

 

● 30 – 60 starts per hour for regulating valves

● 600-1800 starts per hour for modulating valves

 

4. Safety

 

Safety is one of the primary concerns that should be taken into account while selecting diaphragm actuators. It is always the best choice to select the safest and the most reliable option considering the application specifications.

 

For example, if a fire breaks out, the pneumatic diaphragm actuator should be able to maintain the fail-safe position. If the most ideal actuator can’t be used due to other factors, you must use additional components to meet the safety and regulatory specifications.

 

5. Cost

 

Cost is obviously one of the most important factors that needs to be considered. As a rule of thumb, the greater your torque requirement is, the more power will be needed. Subsequently, the larger the actuator, the higher the cost.

 

Furthermore, using additional components to adjust for other shortcomings will also increase the overall upfront cost. However, this will also increase the reliability and durability of the actuator. This may prove more cost-effective in the long term.

 

Remember, being diligent about quality control and being clear about your technical specifications are the most important practices in procuring the right actuator for your application. By picking the wrong pneumatic diaphragm actuator, you will not only fail to operate the valve but also cause damage to the components. The right actuator will ensure long-term use and fewer unexpected shutdowns.