Unit 307 Session 8 Cold water system components

​ COLD WATER SYSTEM COMPONENTS

​The working principles of taps, valves and other terminal fittings

Taps and valves can be divided into five separate categories:

1. isolation valves
2. float-operated valves
3. terminal fittings
4. drain-off valves

Open Ended

What is an isolation valve?

​Isolation valves and drain valves

The main use of an isolation valve is to turn off (isolate) either complete systems, or parts of a system or appliances.

They can be divided into four distinct types:

1. those that isolate high-pressure systems, such as stop taps
2. those that isolate low-pressure systems, such as full-way gate valves
3. those that isolate appliances and terminal fittings on either high- or low-pressure systems
4. those that are used for draining down systems

​Stop taps/valves (high-pressure isolation) to BS 5433 or BS 1010

Stop taps are designed for isolation of high-pressure cold water systems and, because of their restrictive internal design, should not be used on low-pressure supplies.

They are manufactured to either BS 5433 or
BS 1010 for domestic use.

They consist of a brass valve body, a head gear with a rising spindle, a packing gland and a re-washerable loose jumper plate.

Stop taps have an arrow on the valve body that shows the direction flow of the water.

​Full-way gate valves (low-pressure isolation) to BS 5154

Gate valves are used on low-pressure installations such as the cold feed to vented hot water storage cylinders and the cold distribution pipework for indirect cold water systems.

They do not have a washer, instead using a brass, wedge-shaped gate that rises inside the valve.

They are known as ‘full-way’ gate valves because the design allows water to flow at full bore without much restriction to the flow rate.

They should not be used on high-pressure supplies as they allow water to pass by the gate when the valve is under pressure.

​Spherical plug valves (isolation)

Spherical plug valves are used for isolation of appliances and terminal fittings such as taps and float-operated valves.
A variety of styles are available, including with or without a handle (these use a screwdriver slot to isolate the water), or for use with an appliance such as a washing machine.

Hotspot

Where is the rising spindle?

Hotspot

Where is the packing gland?

Hotspot

Where is the packing ?

Hotspot

Where is the Tap washer ?

Hotspot

Where is the Wheel head?

Hotspot

Where is the Packing gland?

Hotspot

Where is the Packing gland nut?

Hotspot

Where is the Non-rising spindle?

​Drain-off valves
Drain-off valves are small valves that are strategically placed at low points in the installation to allow draining down of the system.

Multiple Choice

What is the primary purpose of an isolation valve?

• Increase system pressure

• Control temperature in appliances

• Turn off (isolate) systems or parts of a system

• Enhance water flow rate

Multiple Choice

Research which type of isolation valve is suitable for high-pressure cold water systems, conforming to BS 5433 or BS 1010?

• Full-way gate valve

• Spherical plug valve

• Spherical plug valve

• Stop tap

Multiple Choice

What is the key characteristic of full-way gate valves?

• Designed for high-pressure systems

• Allow unrestricted flow at full bore

• Used for draining down systems

• Equipped with a spherical plug

Multiple Choice

Research which isolation valve is appropriate for low-pressure installations like the cold feed to vented hot water storage cylinders?

• Full-way gate valve

• Brass wedge valve

• Spherical plug valve

• Stop tap

Multiple Choice

What are spherical plug valves commonly used for isolating?

• High-pressure cold water systems

• Low-pressure vented hot water systems

• Drainage systems

• Appliances and terminal fittings

Open Ended

Research what a float operated valve is?

​Float-operated valves to BS 1212

Float-operated valves are used to control the flow of water into cold water storage and feed cisterns, feed and expansion cisterns, and WC cisterns.
They are designed to close when the water reaches a pre-set level.

They are made to BS 1212 and it is important that plumbers recognise the different types.

​Part 1 Part 2 Part 3 Part 4

​There are four basic float-operated valve types:

1 BS 1212 Part 1: Portsmouth pattern and Croydon pattern

2 BS 1212 Part 2: Diaphragm type 3 BS 1212 Part 3: Diaphragm type (plastic)

4 BS 1212 Part 4: Torbeck equilibrium type (WC cisterns only)

​BS 1212 Part 1 Portsmouth pattern float-operated valve

The Portsmouth-type float-operated valve discharges water from the bottom of the valve, which makes it susceptible to back siphonage should the valve become submerged in water.

It should not be fitted on new installations without some form of backflow protection device, although existing Portsmouth-type valves can be repaired and maintained.

​BS 1212 Part 2 diaphragm float-operated valves

These float-operated valves use a diaphragm rather than a washer to control the flow of water and, unlike Part 1 float-operated valves, they discharge water over the top of the valve.

This makes them less susceptible to being submerged in water when the overflow runs and so less likely to cause a contamination issue.

​BS 1212 Part 3 (plastic) diaphragm float-operated valves

The main difference between a Part 2 float-operated valve and a Part 3 float operated valve is that the Part 2 is made of brass and the Part 3 is made of plastic.
They are almost identical in all other respects. It should be noted that plastic float-operated valves are not recommended for cisterns other than WC cisterns because of the risk of freezing and subsequent splitting of the plastic.

​BS 1212 Part 4 equilibrium diaphragm float-operated valve

The equilibrium float-operated valve is a diaphragm valve that works on the principle of equal pressure in front and behind the diaphragm when the valve is open.
No moving parts come into contact with the diaphragm.

It closes the valve when a build-up of pressure occurs in front of the diaphragm due to the float arm closing the pressure relief orifice on the front of the valve.

Hotspot

Where is the Orifice/seating?

Hotspot

Where is the piston?

Hotspot

Where is the leaver arm?

Hotspot

Where is the Washer?

Hotspot

Where is the Inlet?

Hotspot

Where is the Piston?

Hotspot

Where is the Orifice/seating?

Hotspot

Where is the Diaphragm washer?

Hotspot

Where is the Pilot hole?

Hotspot

Where is the Float?

Hotspot

Where is the Leaver arm?

Multiple Choice

Which BS 1212 float-operated valve type discharges water from the bottom and may require backflow protection to prevent back siphonage?

• BS 1212 Part 2: Diaphragm type

• BS 1212 Part 3: Diaphragm type

• BS 1212 Part 1: Portsmouth pattern

• BS 1212 Part 4: equilibrium type

Multiple Choice

What is the key feature of BS 1212 Part 4 equilibrium float-operated valve?

• Discharges water from the bottom

• Uses a piston

• No moving parts contact the diaphragm

• Requires a long leaver arm

Multiple Choice

In what situations should the Portsmouth-type float-operated valve be fitted on new installations?

• Always

• Only if backflow protection is provided

• Only in high-pressure systems

• Never

Multiple Choice

Which part of the BS 1212 standard applies specifically to equilibrium float-operated valves used in WC cisterns?

• Part 1

• Part 2

• Part 3

• Part 4

​Terminal fittings

​Terminal fittings are those that are fitted to sanitary appliances, such as baths and washbasins.

Open Ended

Taps are classed as a terminal fitting; how many types of taps do you know?

​There are several different types, which are:






Pillar taps for baths, washbasins and bidets – these are available for baths (¾-inch tails), washbasins and bidets (½-inch).






High-necked pillar taps for kitchen sinks – similar internal design to pillar taps but designed with a high stem to provide an AUK3 air gap at kitchen sinks.

​Bi-flow mixer taps including monobloc mixers – these are two taps in a single body. A bi-flow mixer has a single spout that is divided down the middle so that the water does not mix until it has exited the tap. It is not a true mixer tap.

​True mixer taps – allow the hot and cold water supplies to be mixed inside the body of the tap. Caution should be exercised as these taps can provide a cross-connection between low-pressure hot (fluid cat. 2) and high-pressure cold (fluid cat. 1).

​Bib taps and hose union bib taps – bib taps are mostly fitted to the wall above cleaners’ sinks and Belfast sinks.







Hose union bib taps are specifically designed for garden use so that a hose may be connected.

Most taps fall into three categories:

1. taps with a rising spindle to BS 1010

2. taps with a non-rising spindle to BS 5412

3. ceramic disc taps.

​Taps with a rising spindle to BS 1010

BS 1010-type taps have a rising spindle attached to a jumper plate and a washer.
When the tap is turned on, the spindle rises, allowing the pressure of the water to push the jumper plate and washer upwards to start the flow of water.
Originally, there were two different types:
1 those taps with loose jumper plates for high-pressure supplies such as mains cold water
2 those taps with fixed jumper plates for low-pressure supplies such as indirect cold water installations and vented hot water supplies.
Both types have a packing gland designed to stop water leaking through the spindle.

​Taps with a non-rising spindle to BS 5412

Unlike BS 1010 taps, these taps do not have a rising spindle. Instead, the spindle has a thread at the end that lifts a hexagonal barrel, with a rubber washer attached, inside the valve head workings.

The spindle is fixed in the head workings by a circlip.

Hotspot

Where is the Tap Wheel head?

Hotspot

Where is the Jumper and washer?

Hotspot

Where is the Packing gland?

Hotspot

Where is the Rising spindle?

Hotspot

Where is the Packing?

Hotspot

Where is the Head workings?

​The design of BS 1010 taps is generic across most manufacturers.

This means that the head workings of one tap will almost certainly fit the tap body of another manufacturer, including stop tap heads.

​Ceramic disc taps

Unlike washer-type taps, ceramic disc taps use two thin, close-fitting, slotted ceramic discs in place of rubber washers.

One of the discs is fixed, while the other is turned by the handle of the tap a quarter of a turn through 90°.

​Ceramic disc tap heads are ‘handed’. In other words, there are specific hot tap head workings, which turn to the left, and specific cold tap head workings, which turn to the right, and they are usually colour coded for easy identification. Ceramic disc taps are not universal. If replacement head workings are required during maintenance operations, the correct type for the make of tap will be needed

Multiple Choice

What is a key characteristic of bi-flow mixer taps, distinguishing them from true mixer taps?

• Single spout divided down the middle

• Mixing of hot and cold water inside the tap body

• Suitable for garden use

• Available in various sizes

Multiple Choice

What type of tap is shown in the picture?

• Rising spindle

• Non rising spindle

• Ceramic disc

Multiple Choice

Why should caution be exercised when using true mixer taps?

• They have a rising spindle

• Provide an AUK3 air gap

• Can create a cross-connection between low-pressure hot and high-pressure cold water

• Designed for specific sinks only

Labelling

Label the diagram

Drag labels to their correct position on the image

Jumper and washer

Packing

Rising spindle

Multiple Choice

What is the primary purpose of hose union bib taps?

• Fitted above cleaners' sinks

• Designed for garden use

• Suitable for bidets

• Used in kitchen sinks

Multiple Choice

What type of tap is shown in the picture?

• Rising spindle

• Non rising spindle

• Ceramic disc

Multiple Choice

How do ceramic disc taps differ from washer-type taps in terms of design?

• Use a rising spindle

• Have a hexagonal barrel

• Have fixed jumper plates

• Use slotted ceramic discs instead of rubber washers

Labelling

Label the diagram

Drag labels to their correct position on the image

Non-rising spindle

Circlip

Washer