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Plumbing Full Course - Part 20

Mohammed Furkhan July 09, 2022


      This is part 20th of the full Plumbing course in Mep.. If you like to access previous parts, you can get them by the end of this post..

Plumbing Valves (contd...)

Pressure reducing Valve (PRV)

We've all heard and used the phrase 'pressure reducing valve' but are they really useful? To some 1. yes! This article is going to look at valves from a plumbing point of view. I hope this helps you understand what pressure reducing valve does and how it works. Let's begin...

The first thing we want to consider is where our toilet tank goes and connects to. We want to ensure that we have enough capacity left inside the tank before any connections are made.

So right now, we should have 1/2 gallons of water remaining inside our toilet tank. Now lets connect the hot water pipes coming off the wall into the tank. As long as the tank has room for more, then the pressure inside will increase and cause the float valve to rise and close the drain hole. This prevents the flow of water from exiting the tank. However, if the tank starts to fill, the pressure inside increases to the point where the float valve cannot hold back the flow of water, and the whole tank empties in seconds.

This is called a pressure reducing valve. It is designed to prevent this from happening by allowing only a certain amount of water through. There are several different types of pressure reducing valves available. The most common one is listed below:

Spring-loaded ball valve - A spring pushes down against a rubber membrane which creates a seal around a small opening. This allows the liquid to pass through, but prevents large volumes from doing so. The disadvantage of this type of valve is that it often needs replacement due to wear & tear. They also tend to leak when under too much strain.

1. How does pressure reducing valve work?

Pressure reducing valves allow water to flow through but prevent backflow from occurring. This allows water to flow freely, but prevents sewage from flowing back into the household. In order to ensure this happens, the valve controls the amount of pressure that exists inside the pipe. To achieve this, the valve uses a spring loaded mechanism which creates a small gap between two components of the device. The opening and closing of the valve occurs by means of a butterfly style disc that sits perpendicular to the line of movement of the water. When the water enters the valve, it pushes the disc down against the force of the spring causing a large opening and allowing the water to pass through. However, as soon as the water leaves the valve, the pressure drops and causes the disc to rise up again, creating a seal and preventing any backflow. Many different types of pressure reducing valves exist including brass and plastic valves. Brass valves contain ferrous materials which make them magnetic and easier to clean, while plastic valves are less prone to corrosion.

2. What are the advantages & disadvantages of using a pressure reducing valve?

Advantages

• Easy Installation – Pressure reducing valves are relatively straightforward to install. They require little effort and can be installed quickly.

• Low Maintenance – Once installed properly, pressure reducing valves should last indefinitely without requiring maintenance.

Disadvantages

• Costly – While they may be simple to install, some pressure reducing valves can be rather expensive.

1. How does a pressure reducing valve work?

A pressure reducing valve is used to control the rate at which water flows through pipes. When the flow exceeds the capacity of the pipe, the valve opens to allow the excess to pass into a reservoir. This allows the pressure inside the pipe to drop until it matches that of the reservoir. Once this happens, the valve closes again. A typical pressure reducing valve consists of two parts; a body and a stem. The body contains a small hole where the water passes through. The stem rests above the hole and contains a spring loaded ball that falls into the hole as soon as the water pressure rises beyond a certain point. A stop inside the body prevents the ball from falling out. If the water pressure drops below a certain level, the spring pushes the ball back towards the top of the hole. This causes the stem to rise, allowing the water to flow freely past the ball.

2. Types of Pressure Reducing Valves

There are 2 types of pressure reducing valves, i.e., diaphragm type and shutoff type. Diaphragm valves sense the pressure of the water passing through them and open a passage only when the pressure reaches a specific threshold. As they open, the diaphragms deflect and actuate a mechanism that then releases the opening. Shutoff valves open automatically when the water pressure reaches a predetermined value.

3. Advantages of Pressure Reducing Valve

Advantages:

a) It controls the flow of water

b) It reduces the pressure of the water

Water Hammer Arrestor

1. A water hammer arrestor is used to prevent damage from excessive pressure surges in the supply lines. They consist of two chambers separated by a small orifice. Pressurized water enters one chamber, where the volume is reduced and suddenly releases through the orifice into the second chamber, causing a brief drop in pressure. This sudden release of energy dissipates into heat, instead of damaging pipes or fittings.

2. Water hammer arrestors are designed to protect against water hammer events. A water hammer event occurs when there is too much pressure buildup in the supply line. Since water hammers occur at certain pressures, they are often referred to as critical pressures. Critical pressures can vary depending on the type of pipe being used and the number of bends and joints. Water hammer arrestors work to prevent these types of events by dissipating excess pressure before it reaches the structure’s internal components.

3. Water hammer arrestors can be installed between pipes in order to reduce stress caused by different rates of expansion and contraction. This allows pipes to expand and contract without breaking.

4. There are several methods to install water hammer arrestors. One method involves inserting the device inside the existing pipe. Another method requires installing the device on top of the existing pipe. The most common placement method is to insert the device directly into the junction between the pipes.

5. There is a wide range of water hammer arrestors available to fit specific purposes. For example, some arrests are designed specifically for commercial applications, while others are suitable for residential use.

6. To determine whether a water hammer arrestor is appropriate for a particular application, consider the following factors:

• Size of the pipe(s) involved

• Number of bends, etc.

A water hammer arrestor is used to reduce pressure fluctuations caused by sudden changes in pipe diameter that can cause annoying noise and vibration in pipes carrying liquids such as hot water. When a liquid flowing through a pipe encounters any kind of change in diameter, the flow speed and/or volume of the liquid increases suddenly. This causes pressure waves in the fluid. It sounds like a strong impact or clap of thunder. A sudden increase of the pressure inside the pipe generates shockwaves that propagate towards the end of the pipe and produce vibrations. This phenomenon is called water hammer.

This may cause discomfort to anyone standing close to the pipe where the vibration is generated. Moreover, this phenomenon causes damage to fixtures and fittings. To prevent this hazard, a water hammer arrestor is installed at the point where the pipe diameter changes abruptly.

2. Advantages of water hammer arrestor

There are many advantages of using a water hammer arrestor. One advantage is that they significantly reduce the possibility of damage to piping due to pressure surges. Another benefit is that they limit the possible transmission of harmful vibration and sound from one location to another. A third advantage is that they help to prevent the escape of air into the liquid. Last but not least, since they are designed to absorb energy, they help to cut down on heat losses that occur when the water flows through the pipe.

• The slow moving water hammer - occurs when the upstream water pressure drops below the downstream water pressure. This results in a reduction of the downstream pressure which triggers a backward rush of the upstream water.

When do we need water hammer arrestor in water supply design?
* For every 9 WSFU 1 WHA is required.
WSFU - WATER SUPPLY FIXTURE UNIT
WHA - WATER HAMMER ARRESTOR

* After every elbow WHA is required.

* One WHA is required in one toilet.

Strainer

1. Filtration and Clarification

In order for water to flow through a pipe from the point of origin to the point of consumption, it needs to be clear and free from impurities. All pipes contain some amount of impurities, but those deposits are removed before the water leaves the tap. However, even though they are filtered, pipes still contain contaminants and minerals that can cause problems in plumbing systems.

2. Water Softeners

Water softeners remove hardness from the water supply. Hardness refers to minerals and salts that make water hard. This is caused when water enters the ground and comes into contact with rocks and other materials. These hard substances can cause many plumbing issues including clogs, rusting of pipes, and corroding fixtures.

3. Sediment Filters

Sediment filters remove sediment that settles at the bottom of a tank. They usually consist of two chambers separated by a membrane. One side contains sand while the other side uses activated carbon to filter particles in the water. There are different types of sediment filters ranging from inline units to countertop filters to whole house systems.

4. Carbon Blocks

Carbon blocks are used to absorb odors in bathrooms. Many homes have a bathroom without air conditioning, while others may have several children with frequent accidents. It is important to have a good odor neutralizer installed to eliminate unpleasant smells. Usually, carbon blocks are placed near a vent or window to allow enough airflow to circulate properly.

Foot valve

A foot valve is a device located at the bottom of a sink faucet or tub/shower faucet that allows water flow through the faucet. A simple but effective design of this type of faucet is called a pressure balanced, which ensures that the water pressure coming from the faucet remains constant regardless of whether the water supply line is turned on or off. Another popular style of foot valves are known as direct acting valves. This style of faucet uses a spring-loaded mechanism similar to those used in traditional toilets. These types of valves are generally better suited for low volume fixtures such as urinals, portable sinks, bathroom showers, etc.

2. Benefits

The benefits of having a foot valve include:

• No additional water supply is needed to operate the fixture.

• Water pressure remains constant as long as the supply line is on.

1. How does a foot valve work?

A foot valve is a type of check valve designed to allow pressure from the water supply to pass through the device while preventing backflow. When you turn off the cold/hot water faucet at the kitchen sink, hot or cold water passes through the valve into the pipe, but once the water stops running, the valve prevents any residual water from going back through the same pipe. This prevents damage to pipes. A typical foot valve has two flaps that sit inside the pipe. As the water flows down the pipe, the force of the water pushes against the flap and opens it slightly, allowing the water to flow. Once the water stops flowing, the pressure in the pipe drops and causes the flap to close again and prevent any reverse flow.

2. Why would I want a foot valve?

A foot valve helps prevent frozen pipes. Frozen pipes happen when water remains in the pipe after turning off the faucet. Over time, this frost expands and creates cracks in the pipe. Without proper insulation, the heat in the house cannot escape, causing the pipes to freeze. To reduce the risk of freezing, install a foot valve.

3. Can I put my own foot valve in place of the current one?

Yes! Most old style valves have a simple spring mechanism that keeps the valve closed until sufficient pressure builds in the pipe, then the valve automatically opens. It doesn’t matter whether you replace the existing valve with something different, it will still work just fine. The only difference is that you may see less water flow since the new valve may be smaller and narrower than the original. However, you could upgrade to a larger model to improve your flow rate.

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