You do not have to be a chemical engineer to join IChemE. Our global membership community includes people from a range of disciplines who have an interest in and/or relevant experience in chemical engineering.

Boilerexpansion vesselreplacement cost

Before applying a generalisation that you read on the internet or given by a colleague, take the time to understand the derivation for that rule of thumb and ensure it applies to your situation

Expansion vessels are key components of any unvented hot water system  and should be present in all pressurised hot water systems. Closed water system components can be damaged by increases in pressure and expansion vessels help to maintain pressure levels. They are usually located in or near the water heater and are filled with air or a gas such as nitrogen. They will often be available as part of an unvented kit.

The SharkBite washing machine angle valve features a quarter-turn angle stop valve and is ideal for use in washing machine installations. View now.

When a hot water system is running as usual, the expansion vessel will regularly partially empty and then refill, exchanging water with the system. However, expansion vessels are known to be points that run the risk of bacterial growth as they can suffer from low flow rates or stagnant water. This is particularly true if the system is unused, or the pressure and temperature remain steady over a period of time. In that case the normal fill and replace cycle won’t be naturally changing the water and bacteria can flourish.

RULES of thumb are sometimes misleading. Engineers often discuss rules of thumb for pipe sizing. Velocity (1–4 m/s) and Reynolds number (>10,000) are cited, as are pressure drop (20-80 kPa/100 m) and shear stress (>5 Pa).

The flow through expansion vessel from Hamworthy has an internal bladder manufactured in Butyl rubber to limit the risk of bacteria growth, including Legionella, which makes it particularly suited to healthcare premises.

The purpose of a hot water recirculation system is to provide you with hot water faster, so if you find yourself waiting for hot water when you turn on the tap, ...

The lesson is that general sizing rules must be tempered with good engineering. Before applying a generalisation that you read on the internet or given by a colleague, take the time to understand the derivation for that rule of thumb and ensure it applies to your situation. Pipe sizing isn’t an exact science and rules of thumb are perfectly acceptable when choosing a size, but this should be done with eyes open.

Gas Hot water heater! Independence, KS. Gas water heater in Pittsburg, KS. $120. Gas water heater. Pittsburg, KS. Electric Water Heater.

Pharmaceutical engineers often cite “turbulence” as the driving criteria for sizing the piping for high purity water. The idea is that turbulent flow, defined as Reynolds number >4,000 (or >10,000, depending upon which engineer is speaking), greatly reduces the propensity for a biofilm to establish on a pipe wall. However, there is always a laminar layer at the pipe wall; it is many times deeper than a typical biofilm thickness even at a Reynolds number of 50,000. Studies show that microbes will tightly adhere to stainless steel pipe walls when the shear stress is less than 8-10 Pa. As seen on the charts, the Reynolds number needs to be well over 50,000 to achieve 10 Pa shear stress at the wall.

Expansion vessels contain air, or an inert gas, and water from the system. These are separated within the vessel by a membrane – either in the form of a rubber sheet (or diaphragm) or a bladder. As cold, pressurised mains water is heated in an unvented hot water system the water expands and this pressure builds. Water in the expansion vessel therefore also expands and the air within the vessel compresses to absorb this increased volume and, hence, the pressure. When the water cools – and the pressure reduces - the water level within the expansion vessel drops again.

Catch up on the latest news, views and jobs from The Chemical Engineer. Below are the four latest issues. View a wider selection of the archive from within the Magazine section of this site.

Another sizing approach is based upon existing infrastructure limitations. For example, your plant’s chilled water pressure or a pump’s capabilities might limit the maximum pressure drop. However, you might not be able to provide a target of, for example, 60 kPa/100 m. Instead, the pipe sizing might simply be based on the available pressure drop regardless of how that fits into the generality.

I made these to help me visualise the relationships between flow rate and pipe size. From these charts you can see that the “rules” are not consistent. For example, if you hold velocity constant at 2 m/s, the pressure drop varies from about 10 kPa/100 m for 12-inch pipe to >125 kPa/100 m for 1-inch.

Combi boiler

Florida Water Technologies is a quality distributor of affordable water softeners in Jacksonville. Our Florida water filtration systems are built with the ...

Hydronics

We can provide standalone flow through expansion vessels and a flow jet valve that diverts part of the water flow in the system into the vessel, preventing water stagnation and guarding against the breeding of harmful bacteria – most notably legionella (which causes the potentially fatal Legionnaires disease).

A flow through expansion vessel reduces the risk of legionella growth in an unvented system, reduces the amount of pipework in the system and gives more flexibility for maintenance and replacement.

Products · Plumbing & Flow Control Solutions · Connections · AquaLock Push-to-Connect Fittings · AquaLock Plastic Fittings ...

The ¾" to 4" size cast 316SS duplex basket strainers by all three manufacturers have a ball valve style flow diverter, so just like moving a ball valve lever, ...

Expansion vesselpressure

3/4 in. Bronze NPT 350 psi Backflow Preventer. Quick View. Part #W975XL3F. Item #9753819.

A rule of thumb that incorporates pipe size is to choose liquid lines to handle a velocity of 1.5 +d/10 where “d” is the pipe diameter, inches. This gives 1.6 m/s for 1-inch and 2.5 m/s for 10-inch piping, and about 20 kPa/100 m pressure drop. Similarly, gas lines can be sized for 20d m/s and steam lines 35 m/s (maximum).

In order to meet the needs of our customers we can provide standard unvented kits with standard expansion vessels, or a standalone flow through expansion vessel with flowjet valve.

Also consider the nature of the fluid being pumped and the material that the piping is made from. Corrosive fluids such as acids, and abrasive fluids such as slurries, will tend to be more aggressive toward the piping at higher velocities. Higher velocities will also create greater water hammer if valves are suddenly closed. If the fluid carries large particles, such as sand, the velocity should exceed the settling rate of the particles (typically about 1 m/s).

expansiontank中文

Flow through vessels have been specifically developed to reduce the risk of stagnation and contamination from slow moving water. They do this by keeping water moving through the expansion vessel using a Flowjet valve.

Cartridge pressure reducing valves are designed for durability and reliability, effectively regulating pressure to certain functions. This will result in a long ...

Given a flow rate and pipe size, these charts give a Reynolds number and velocity. The charts trace any one parameter along with pipe size and yield the remaining flow parameters.

One approach is to perform a life-cycle cost analysis that balances operating and maintenance costs against the initial capital investment. This analysis usually results in a velocity around 2-3 m/s, giving that rule of thumb. More expensive piping materials and larger pipe sizes tend to favour sizing for higher velocities whereas common materials and smaller sizes indicate lower velocities.

Use the rules of thumb judiciously. Let them give you a first estimate, and use them again to reality check your final selections. Pipe sizing exercises are filled with calculations, but the formulas used in those calculations are themselves based upon empirical data and sometimes fuzzy data. These notions make the whole sizing process an engineering art form, which gives my creative side great joy.

The pipe size choice may be influenced by other factors: 1) Pipes are typically one size larger on the suction side of a pump than on the discharge; 2) a smaller-than-expected size might be selected to make installation in tight quarters easier; 3) when a very small line, such as ½” or ¾”, is acceptable, the engineer might upsize it to 1” or even 2” to provide strength, so someone who steps on the line won’t break it; and 4) short pipelines will be smaller diameter than long ones with equal pressure drops.

Expansion vesselboiler

A conversation with the experts: watch the recordings of our previous webinars and sign-up to attend future online webcasts.

How do you determine the pipe sizes for a system? The first step is establishing the process requirements: flow rates, fluid properties, and pipeline configuration. Many engineers then apply a rule of thumb that says to use a velocity of 1.5 to4 m/s. Higher velocities mean higher pumping cost and possibly damage to the piping due to erosion or water hammer. Lower velocities mean larger (more expensive) piping and possibly problems from fouling or solids depositions in the pipes due to insufficient turbulence.

Duplex strainer or twin basket strainer is a type of filter built into a fuel, oil or water piping system and it is used to remove large particles of dirt and ...

Best Underfloor Heating Solutions with cost-effective and easy installation. Get a free quote & buy other heating products like thermostats & heated ...

This is the fifth in a series that provides practical insights into on-the-job problems. To read more, visit the series hub at https://www.thechemicalengineer.com/tags/rules-of-thumb