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Tag Archive: check valves & control valves

1. The Importance of Good Information About Valves

   January 6, 2015 4:34 pm 3 Comments

   Proper valve selection is critical for ideal operation of any system. Improper valve selection can cause system underperformance or failure. The greatest problem when selecting valves is incorrect information.

   Often, we may only have access to incomplete or dated information regarding valve applications. Do we know enough about the system the valve will be used in or the main purpose of its use? This “bad information” can create a situation where the theoretical situation does not match reality.

   Good Information is Key

   “Bad information” comes in many forms. Original design specs might be difficult to obtain, and having those specs does not guarantee success. Occasionally, specs aren’t properly updated. Information that was good at first can fail to incorporate changes in process conditions. If the actual pressure, temperature, flow-rates or the media is different than that which was used to select the valve, it may fail or fail to work properly.

   When choosing a gate, globe, ball or check valve, we always want the valve to be operating in the full open or closed position. Control valve selection, however, targets 40% to 60% open for normal flows. When most control valves operate below 20% open or over 80% open, they can lose their ability to control properly.

   What information is required to properly size a valve? Fluid type, operating pressures and temperatures upstream and downstream of the valve, and the flow rates associated with these conditions are required information to have.

   Knowing What is the Right Valve for the Application

   There are many different types of valves available. They do not all work the same way or for the same purposes. Each valve type has its advantages and disadvantages.

   For proper control valve selection, it is important to understand how the valve is used to control system flow. For example: is the system tuned for a constant set point, or is it set to modulate a variable flow over time? The layout of the piping system and locations of reducers and elbows also impact valve performance.

   Often, choosing what seems to be the most efficient valve might not be the best valve for application. Replacing a valve “in kind” with an upgraded version of an older valve might actually do more harm than good.

   Poor Performance – Get Good Information

   Unfortunately, the blame for poor performance often lands on the installed valve when it is actually bad information that caused its failure. Simply repeating the bad information to select a different valve is doomed to have the same results. When DFT Inc. is asked to troubleshoot an installation, we start by collecting all of the available information and check for “bad information” concerning flow conditions and application mismatches with respect to the installed valves.

   Take the time to get good information. Fortunately, the information is more readily available today than it has been in the past through trending information. If you can provide actual system operational information, your chance for success increases significantly.

2. Why Are We Always Repairing This Valve?

   November 24, 2014 3:18 pm Comments Off on Why Are We Always Repairing This Valve?

   I just had my boss read me the riot act – again. I exceeded my valve maintenance budget for the year—with three months to go. She certainly won’t buy into the fact that I did not get the budget that I asked to have. It’s up to me to determine how to lower our costs to meet the budget.

   So I start to look at the bad actors.  Sure enough, there are a handful of valves that stand head and shoulders above the rest … all of them are control valves.  By keeping these valves running properly, our efficiencies are up.  But instead of getting a pat on the back for improving output, I get a slap on the wrist for wrecking a budget.  What can I do?

   

   One thing that you can do is to take a look at how the control valve is sized. Trending data is excellent for determining the actual operational conditions; compare this data to the information given in the valve specification. Control valves are designed with these factors in mind:

   • Fluid type
   • Upstream pressure
   • Downstream pressure
   • Flow Rate
   • Temperature

   For proprietary fluids, we need to know information concerning the density and vapor pressure of the upstream fluid if it is a liquid, or the molecular weight and other factors if it is a gas.

   Next, we need to understand where the control valve should be operating.

   • Less than 10% open – avoid since the valve will quickly wear;
   • Plan to keep the range of operation between 20% and 80% open;
   • Try to keep the “normal” control range between 40% and 60% open;
   • Greater than 90% open – avoid since the valve will tend to wash out (erode from constant water flow).

   If we have trending information on the valve, we can quickly see if they are operating in the proper operating range. If not, give the valve manufacturer the operational conditions and ask them to tell you where the valve is operating.

   Always keep in mind is that the valve trim size is determined by the maximum flow condition. The unintended consequence is often that control valve becomes oversized for the application.

   The bottom line is that an oversized control valve is more expensive to install, has more expensive parts to replace, and wears out more quickly.

   The HI-100™ is a low-cost valve with robust features designed for long service life. Using this control valve will help you keep your maintenance budget in line.

   

3. Harsh Conditions Call for Tougher Equipment

   November 22, 2013 8:04 pm Comments Off on Harsh Conditions Call for Tougher Equipment

   Certain industrial environments are harsher than others, and not all valves can take the heat. For example, the pulp and paper industry utilizes processes called batch steam cooks. The processes involve very hot steam, tough chemicals, and a high level of repetition- not ideal for just any valve. Pulp is one of the most abundant raw materials in the world and the United States is the second biggest supplier of paper across the globe. That means there are many mills in need of durable, reliable equipment. Some mills have also started producing pulp for the textile industry, another huge global market that requires mass quantities of material.

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4. Keeping Up With The Food & Beverage Industry

   October 15, 2013 7:57 pm Comments Off on Keeping Up With The Food & Beverage Industry

   The food and beverage industry in the United States is undergoing significant changes when it comes to trends, regulations, and tastes. Consumers are looking for healthier options, more attractive packaging, and more local ingredients. The industry has risen to the challenge and is rapidly evolving to meet these new consumer desires. Food processing has shed its reputation for unhealthy and unattractive food as new technologies allow companies to mass produce up-to-the-minute products such as guacamole and hummus without adding tons of preservatives. Regulations to lower sodium and trans fat counts as well as national movements to incorporate more healthy foods into school lunches has also presented a challenge to the food and beverage industry, but it was a challenge that was met with innovation and success. The industry is booming and food processing companies have come up with new and fresh ways to stay competitive and give consumers exactly what they are looking for.

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5. Metering the Energy Boom

   September 4, 2013 8:00 pm Comments Off on Metering the Energy Boom

   There’s no doubt about it- the North American oil and gas industry has been booming over the past year. As technology advances, it has become possible to discover large new fossil fuel deposits and extract them from places previously thought unreachable. This is especially true of the vast shale formations across the country, namely the Eagle Ford, Barnett, Bakken, and Marcellus shale plays, among many others. The Bakken formation, which lies underneath parts of North Dakota, Montana, and Saskatchewan, has been very popular recently as it was discovered to hold vast quantities of shale oil and natural gas with estimates in the billions of barrels of oil and trillions of cubic feet of natural gas.

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