2023年8月29日星期二

Anatomy of A Exhaust Valve Failure

First, the keys to exhaust valve longevity are: Precise contact between the valve face and the valve seat and a good fit between the valve stem and the valve guide. In-flight, the pilot must keep cylinder head temperatures within normal limits to avoid damage.

Exhaust valves burn when they fail to seat properly and, as a result, can't efficiently transfer heat to the cylinder. Ultra-hot gasses scorch these valves beginning at their thin rims. This damage erodes and weakens the valves, exacerbates the poor seating problem, and dramatically accelerates wear. Without intervention, the exhaust valve can fail with potentially disastrous consequences.


Exhaust valve 

Determining Valve Health

Green Means Stop

When an exhaust valve doesn't seat properly, ultra-hot gasses can leak around the thin valve rim and create hot spots. The first indication of a problem is usually an asymmetric pattern of deposits on the valve face.

Normal buildups on the valve face tend to be red, orange, or gray in color. The valve face can turn yellow or green when the temperature becomes abnormally high. When a portion of the exhaust valve itself turns green, it means the valve is severely burned and weakened, and the valve should be replaced immediately. In this case, “Green means stop.”

The green pattern is usually crescent-shaped and expands from the edge to the center of the valve. In advanced cases, two crescent patterns may emerge on opposite edges of the valve.

>>Shop for exhaust valves here


Red Symmetrical Pattern on the Valve Face

Unburned byproducts of combustion frequently leave red or orange deposits on the valve face. These colorful buildups tend to be thickest at the center of the valve (where the temperature is relatively cool). The cooler the valve, and the richer the fuel/air mixture, the thicker the deposits are going to be.

Don't be alarmed by the reddish color of these buildups. As long as the pattern is symmetrical and resembles an overcooked pizza, it's probably healthy.

 

Brass exhaust valve


Valve Rotation

Exhaust valves are designed to rotate, and this rotation is essential to valve longevity since it helps prevent deposits from building up around the seat, stem, and guide. At a typical 2,400-rpm cruise, each exhaust valve opens and closes 1,200 times a minute, and each valve rotates once per minute.

Precise alignment of the rocker arm is essential for proper valve rotation. A poorly aligned rocker arm can wear out a valve guide within 100 hours of engine operation – and that wear can cause improper valve seating, hot spots, and valve damage or failure. Watch through the borescope as you turn the propeller by hand and pay careful attention to how the exhaust valve opens and closes. Note any “side step.” The more a valve shifts sideways as it enters the seat, the more worn the valve guide is likely to be.

Also, when you find a burned valve, make sure to closely inspect the rocker arm. If the toe of the rocker arm isn't striking the valve squarely, it will cause valve guide wear, and the valve to seat improperly. A poorly aligned rocker arm can prevent the new valve from rotating properly and result in premature valve wear.


The Final Words

Traditional cylinder compression checks are still valuable diagnostic tools. Low readings on a compression test, and the sound of air leaking from the exhaust, are obvious warning signs of valve problems. Combine this information with the clear and colorful images you can see through a modern borescope and you will gain a much fuller picture of an engine's condition. We are an exhaust valves supplier. Please feel free to contact us if you need them!

2023年8月25日星期五

What are the Features of Gate Valves?

The gate valve is one of the most commonly used cut-off valves, used to cut off or connect the medium in the pipeline. The shrinkage of the diameter can reduce the size of the parts, reduce the force required for opening and closing, and expand the application range of the parts. But after the diameter shrinks, the fluid resistance loss increases.


The gate valves have the characteristics: Low fluid resistance Applicable pressure and temperature range, etc. It is one of the most commonly used cut-off valves, used to cut off or connect the medium in the pipeline.


Domestic and abroad low-pressure gate valves generally use cast iron materials. Cast iron gate valves often have serious problems such as freezing and cracking of the valve body and falling off of the gate. The carbon steel stem of the cast-iron gate valve is easy to rust, the quality of the packing gasket is poor, and the internal and external leakage is serious.


Diameter shrinkage can reduce the size of parts, reduce the force required for opening and closing, and expand the application range of parts. But after the diameter shrinks, the fluid resistance loss increases.


Gate Valve

 

So more features of gate valves


1. Overall rubber encapsulation: The gate adopts high-quality rubber for the overall inner and outer rubber. European first-class rubber vulcanization technology enables the vulcanized gate to ensure accurate geometric dimensions, and the rubber and ductile cast gate can be firmly connected, which is not easy Good shedding and elastic memory.


2. Lightweight: The body is made of high-grade nodular black cast iron, and the weight is about 20%~30% lighter than the traditional gate valve. It is easy to install and maintain.


3. Precision casting valve body: The valve body adopts precision casting, and the precise geometric dimensions make the inside of the valve body without any fine processing to ensure the sealing of the valve.


4. Flat-bottomed gate seat: The traditional gate valve often deposits in the groove at the bottom of the valve due to foreign objects such as stones, wood, cement, iron filings, sundries, etc. after the pipe is washed with water, which can easily cause water leakage.

The bottom of the elastic seat-sealed gate valve adopts the same flat-bottom design as the water pipe machine, which is not easy to cause debris siltation and makes the fluid flow unimpeded.


5. The opening and closing torque are small, and the opening and closing are more labor-saving. Because the direction of the gate movement is perpendicular to the direction of the medium flow when the gate valve is opened and closed, the opening and closing of the gate valve is more labor-saving


6. Small fluid resistance: because the internal medium channel of the gate valve body is straight, the medium does not change its flow direction when flowing through the gate valve, so the fluid resistance is small.

 

We are a gate valves supplier, please feel free to contact us if you need them!

2023年8月21日星期一

How To Maintain The Ball Valve

Ball valves have a long service life and a maintenance-free period. They must depend on several factors: normal working conditions, suitable temperature-pressure ratios, and reasonable corrosion data.

1. When the ball valve is in the closed state, the pressure fluid is also in the valve body.

2. Before repairing, please clear the pipeline pressure and make the valve open.

3. Please disconnect the power and air source before repairing.

4. Before maintenance, separate the actuator from the base.

5. Before disassembly, please remove the pressure of the upstream and downstream lines of the ball valve.


Cast Iron Ball Valve


6. When disassembling and reorganizing, prevent damage to the parts, especially the sealing surface of non-metal parts, and use special tools to take out the o-ring.

7. When installing the flanged ball valve, the bolts on the flange must be symmetrical and then tighten gradually.

8. Ball valves are available in different materials, such as cast steel ball valves or stainless steel ball valves. The tilting agent should be compatible with the rubber parts, plastic parts, metal parts, and working medium (such as gas) of the ball valve. When the working fluid is gas and gasoline (GB484-89) can be used to clean metal parts, non-metal parts can be cleaned with pure water or gasoline.

9. After cleaning, the cleaning gent evaporates, and the ball valve can be assembled, but it cannot be stored for a long time, otherwise it will rust or become dirty.

10. Before assembling new parts, cleaning is also necessary.


Maintenance of marine ball valves


Ball valves are the type most often found on boats compared to other types such as gate valves and butterfly valves. They are also known as seacocks when they are mounted near a hull opening to either admit water from or expel water to outside the hull. They’re called ball valves because they use a solid ball with a hole through its middle to control the flow. The ball rotates with the handle to align the hole with the inlet and outlet to allow flow through the valve. Turned 90 degrees, the inlet and outlet are blocked and prevent flow. They are best used as shutoff valves because they only need a quarter turn to operate and because the position of the handle conveniently indicates the state of the valve. When the handle is parallel to the flow direction, the valve is open, when perpendicular, it is closed.

Ball valves are not very high maintenance parts. Other than worn O rings that seal the ball inside the valve body, keeping the valve clean and free-turning with a little lubrication is all it needs. It’s when a valve looses its lubrication and debris or corrosion builds up that it can become hard to turn. If you apply too much force to a plastic valve, the handle can break off leaving the valve inoperable and you must repair or replace it.


Ball Valve

Ball Valve


Follow these steps to maintain a ball valve:

1. If practical, remove the valve from the boat so you can inspect it and more easily work on it.

2. Clamp one end of the valve firmly in a vise but not so tightly that you deform or crack the valve.

3. With a large wrench, unscrew the other end.

4. Use water to flush out any sand and dirt from both parts.

The particular valve shown in this post was on the galley drain hose that connects to the cockpit scupper drains above the through-hull fitting on Summer Dance. The valve is angled downward slightly away from its outlet and so acts like a sediment trap for the cockpit drains. Normally, valves like this should at least be angled toward the through-hull so that they don’t trap debris. Unfortunately, the drain funnel that feeds into this valve is too low for that. In situations like this, clean the valve more often than normal to minimize the scoring shown below.

5. Turn the valve handle to the open position, remove the screw that attaches the handle to the valve, and pull the handle straight off.

6. Reach inside the valve body with one finger, stick it in the ball hole to grip the ball, and rotate the ball back and forth until you can pull it out. It should be tight but come out with enough persuasion. The hardest part is getting the handle stem out of its hole.

7. Clean all the parts thoroughly with soap and water. Inspect the O rings for wear and replace as necessary. If the ball and valve body are excessively scored or worn to the point that the valve leaks too much when closed, replace the entire valve.

8. Apply a good quality silicone or Teflon marine lubricant to the O rings and wear surfaces.

9. Reassemble the valve in the reverse order that you disassembled it. Reinstall the small O ring between the ball and handle after you reinstall the ball or it could get pinched in the valve body and prevent proper fit of the other parts. Be sure it seats fully before you reinstall the handle.

10. Reinstall the valve in the boat. Apply Teflon tape to any threads and check for leaks and proper operation.


Repeat this job every couple of years depending on how often you sail and how often you use the valve. At a minimum, work all valves annually to prevent them from sticking. We are ball valve suppliers. Please feel free to contact us if you are interested in our products.

2023年8月15日星期二

Difference Between Gate Valve And Butterfly Valve

Gate valves and butterfly valves are two very common valves. The two differ greatly in their respective structures, methods of use, and adaptation to the working environment. This article will help users better understand the difference between gate valves and butterfly valves, so as to better help users choose valves.


Before explaining the difference between gate valves and butterfly valves, let's take a look at their respective definitions. Perhaps from the definition, you can carefully find the difference between the two.


A gate valve, as the name suggests, can cut off the medium in the pipeline like a gate valve. It is the valve we use in production and life. The opening and closing part of the gate valve is called the gate, which is used for lifting movement. The moving direction of the shutter is perpendicular to the flow direction of the medium on the fluid line. A gate valve is a kind of cut-off valve, it can only be fully open or fully closed, and the flow cannot be adjusted.


Difference Between Gate Valve And Butterfly Valve


A butterfly valve is also called a flap valve. The opening and closing member is a disc-shaped disc that is fixed on the valve stem and rotates around the valve stem and valve shaft for opening and closing. The direction of movement of the butterfly valve is to rotate in place, and it only needs to rotate 90° from fully opening to fully closing. In addition, the butterfly valve itself does not have self-locking capability. It needs to install a turbo reducer on the valve stem. With it, the butterfly plate has the self-locking ability and can also improve the operating performance of the butterfly valve.


To understand the definition of gate valve and butterfly valve, the difference between gate valve and butterfly valve is introduced below:


1. Differences in athletic ability


In the above definition, we understand the difference between gate valves and butterfly valves in the direction of movement and the way of movement. In addition, since the gate valve can only be fully opened and fully closed, in the fully open state, the flow resistance of the gate valve is small; in the fully open state, the thickness of the butterfly valve produces resistance to the flowing medium. In addition, the opening height of the gate valve is high, so the opening and closing speeds are slow; while the butterfly valve can be opened and closed only by rotating 90°, so the opening and closing speeds are fast. Contact us about our products.


butterfly valve

Butterfly Valve


2. The difference between function and use


The gate valve has good sealing performance, so it is often used in pipelines that require strict sealing and do not need frequently repeated switching to cut off the circulating medium. Gate valves cannot be used to regulate flow. In addition, due to the slow opening and closing speed of the gate valve, it is not suitable for pipelines that need to be closed urgently. The butterfly valve has a wide range of uses. The butterfly valve can not only be used for truncation but also has the function of adjusting the flow rate. In addition, the butterfly valve opens and closes quickly, and can also be opened and closed frequently, which is especially suitable for occasions that require fast opening or cutting.

The size of the butterfly valve is smaller than that of the gate valve, and the weight is lighter than that of the gate valve. Therefore, in some environments with limited installation space, it is recommended to use a more space-saving wafer butterfly valve. Among the large-diameter valves, the butterfly valve is the most used valve, and the butterfly valve is also recommended for conveying medium pipelines containing small particles of impurities.

Butterfly valves have gradually replaced other types of valves under many working conditions and have become the first choice of many users.


3. The price difference


Under the same pressure and the same caliber, the price of gate valves is higher than that of butterfly valves. But the diameter of the butterfly valve can be made large, and the price of the large-diameter butterfly valve is not cheaper than the gate valve.


We are a butterfly valve supplier. Please feel free to contact us if you are interested in our products.

2023年8月11日星期五

The Differences Between Ball Valves And Butterfly Valves

When it comes to finding the right valve for your marine or industrial job, ball valves and butterfly valves often take center stage.


Contents:

• Understanding The Butterfly Valve

• Understanding The Ball Valve

• Ball Valves VS Butterfly Valves

• Selection Criteria

• Find The Right Valve for The Right Project


Understanding The Butterfly Valve



Cast steel Butterfly valve

Butterfly Valve


A butterfly valve has a disc (E) driven by a lever or handwheel (A). When closed, the disc is perpendicular to the pipe flow direction. A seal (F) which seats within the valve body (D) ensures a tight closure with the valve disc. A butterfly valves valve characteristics are close to a linear relationship between the flow rate and the stem (C) position. The butterfly valve can be controlled manually, electrically, or pneumatically.


At larger diameters, butterfly valves are generally regarded as cheaper than ball valves. They have the least amount of parts and are relatively lightweight, requiring less support. The weight advantage of butterfly valves to ball valves can be significant at larger pipe diameters. There is a higher probability of leakage at high-pressure differences between the sides of a butterfly valve disc and the seal compared to a ball valve. Also, in applications with large pipe diameters, this high-pressure difference makes it difficult to open the valve, thereby requiring a bypass valve to balance both side’s pressure before the valve can be opened.


There is a pressure drop across the butterfly valve as the disc remains inside the flow even when fully open. This hinders using butterfly valves in process streams that need to be pigged, such as in the oil and gas industry. Butterfly valves are typically ON/OFF valves and are not suitable for precise fluid flow control.


Understanding The Ball Valve



Cast Iron Ball Valve

Ball Valve


ball valve has a hollow spherical ball (F) that is pivoted at one or both ends. The top end of the ball is attached to a shaft (C), which is rotated by a handle (A) to change the valve position to open or close. When fully open, the hole in the ball lies parallel with the pipe flow direction. The ball rests on a seat (E) inside the valve body (G). The ball valve can be controlled manually, electrically, and pneumatically.


Ball valves can also have three-way or four-way flow directions in a T or L shaped bore. A ball valve’s flow characteristics can be read in our technical article on controlling fluid flow with ball valves.


The bore in a ball valve can vary from a size smaller than the pipe diameter (reduced port or reduced bore), a size equal to the pipe diameter (full port), or a V-port design. The design of the ball does affect flow characteristics. A ball valve can have a pressure drop across the valve in a reduced port ball valve or almost zero pressure drop in a full port ball valve, while a V-port design is ideal for stable flow control.


Unlike butterfly valves, ball valves have zero leakage when fully closed. The fluid pressure upstream of the valve pushes the ball against the seal, ensuring a positive shutoff position. Ball valves will easily open at a high-pressure difference on both sides of the valve and therefore do not require a pressure-balancing bypass.



Ball Valves VS Butterfly Valves



Several common features


They are both quarter-turn rotary valves, which require a 90-degree rotation from opening to closing.

These two materials are usually composed of cast iron, stainless steel, and brass.

Each valve effectively regulates the flow of most types of gases and liquids in a wide temperature range.

They are relatively cheap, durable, and reliable.

Both ball valves and butterfly valves are easily available through valve distributors.


These similarities do not mean the valves are interchangeable in all process functions. Instead, it suggests and corroborates why we need to take a closer look at the valves characteristics and what applications to use each valve. Let's take a look at the difference between ball valves and butterfly valves, and how they affect their use:


Differences


Design

Generally speaking, the ball valve is a ball with a hole. A butterfly valve usually consists of a disc mounted on a rotating shaft.

Features

When using a ball valve, turn the valve handle to block or partially block the hole on the ball or open the flow of gas or liquid through the valve. When using a butterfly valve, turning the valve handle turns the disk 90 degrees, to either fully open or fully block the flow of gas or liquid through the valve.

Pressure

One advantage of the ball valve is that it almost always rotates, no matter how much pressure is applied on the supply side. Once opened, the pressure hardly drops because the hole in the ball allows 100 percent of the gas or liquid to flow. The structure of the butterfly valve makes a part of the valve disc always interfere with the flow of liquid or gas. This means that when using a butterfly valve, there will always be a pressure drop. This also means that the butterfly valve may be difficult to open, and a bypass valve may be needed to create balance in the lines before the large butterfly valve can work properly.

Uses

Ball valves are more effective in sealing than butterfly valves, so ball valves are generally more suitable for projects involving the flow of gas. The cost of construction and maintenance of butterfly valves is usually low, so they are often used in large municipal water supply and sewer projects. They are also common in projects that control the flow of river or stream water.


Selection Criteria



The following criteria can be considered before selecting between a butterfly valve and a ball valve:


ㆍApplication: Butterfly valves are commonly used in water-based processes such as sewages, beer and soda production, etc. They are popular in chemical, agricultural, waste treatment plants, and food industries, partly because they are easy to clean. Ball valves can handle both liquid and gases with some solid particles (slurry). They are common in process plants, power plants, petroleum refining, oil, and gas exploration as they can be pigged for cleaning.

Flow capacity: Butterfly valves can provide a larger flow capacity as they are readily available at a larger pipe diameter than a ball valve.

ㆍSealing: Ball valves provide a tight seal in process applications that require zero leakages when shutoff.

ㆍOperating condition: Ball valves can operate up to 1,000 bar and 400 degrees Celsius. Butterfly valves typically operate at a lower pressure (less than 50 bar) and temperature (less than 250 degrees Celsius).

ㆍFlow regulation: Both valve types can be used for on/off control and proportional control, but ball valves are typically used for proportional due to better flow regulation.

ㆍPorts: A butterfly valve can only have two ports, while a ball valve can have more than two ports.


Find The Right Valve for The Right Project



Ball valves and butterfly valves are universal, relatively cheap, and can stand the test of time. Which one is suitable for which project depends on the size and scope of the task. If you need help determining whether a project requires ball valves, butterfly valves, or other types of valves, please contact a qualified valve distributor today

2023年8月3日星期四

The Difference Between Ball Valve And Gate Valve

Gate valves and ball valves are commonly used valves to control flow, but there are important differences between them.

All types of valves are essential to operate countless versions of machinery and equipment, spanning many industries and applications. It is hard to imagine an environment without valves. Having said that, not all valves are the same, and they are definitely not one size fits all parts.

It is important to choose the right valve, so understanding the application, advantages, and advantages of each valve is the key.


Understand the ball valve


Cast steel Ball valve


The main difference between ball valves and gate valves is their structure. They work similarly but have different structures.

Ball valves are so-called because they have a stem and a ball. There is an opening inside the ball. When the valve is opened, this opening is aligned with the pipe, allowing free flow. Turn the control lever to rotate the ball so that the opening is perpendicular to the flow and close it.

These valves are also very durable and can be used for a long time even in the case of heavy use or long periods of non-use. Ball valves are reliable, but they do not provide good control, so in situations where you want a simple shutdown or start without fine-tuning the control, it is best to stick to ball valves. This is why many people simply refer to these valves as "shut-off valves."

When the operator needs to open and close the equipment without losing pressure, the ball valve is also an ideal choice. They have a good seal because the ball blocks the flow, and they are easy to operate, just simply turn the valve handle, and then it can be confirmed visually.

Having said that, the cost of ball valves may be a little higher than gate valves. Another potential disadvantage is the space required for ball valve operation. In order to use the ball valve lever, the operator needs to ensure that there is a complete 90-degree turn.


Understanding gate valves


DIN Cast Iron Non Rising-Stem Gate Valve


Similarly, due to the difference in structure between ball valves and gate valves, the working principle of gate valves is different from that of ball valves. They control the flow through a gate that is lifted out of the passage for fluids or other materials. The door can be round or rectangular. The operator usually controls the valve by rotating the knob to raise or lower the gate, thereby controlling the flow.

The gate valve does not have the immediate closing function of the ball valve, which is one of the main differences. However, they do provide finer tuning control of material flow and flow pressure. The gate valve does not need to be closed immediately, but in applications where it is not required but with a high degree of control, the gate valve is a better choice than the ball valve. For example, in the case of high water pressure, the gate valve can prevent the formation of a water hammer.


Choose the right valve


The decision to use a ball valve or a gate valve depends on various factors, such as price, location and method of use, and the material passing through the valve. You may find that you have chosen one or both. We are a ball valve and gate valve supplier. If you are interested in our products, please contact us now!

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