Plumbing #1 ( Potable Water Systems ) Flashcards
What are the measurements & conversions for the operation, installation & repair of potable water systems?
•Water weighs 10lb. per imperial gallon
•Water weighs 8¼ lb. per us gallon
•Water weighs 1kg per litter
• 1000 cm³ = 1 litre
Listing agencies include:
•( IAPMO ) = International Association of Plumbing & Mechanical Officials
•National Sanitation Foundation
•( ULC ) = Underwriters Laboratories Canada
•( CSA ) = Canadian Standards Association
Water closet waste is stored in the…
Black water tank
What are listed components?
Listed refers to the requirements that materials & components have been tested and approved of for use in their intended application.
Waste water from fixtures using potable water is stored in the…
Grey water tank
The two purposes of the plumbing system are:
• Supply hot and cold potable water to the fixtures
• Dispose of waste in a sanitary manner.
What is potable water?
Water that is safe for human consumption.
Where is potable water stored in RVs?
In the fresh tank.
The potable water distribution system consists of:
• Freshwater tank
• Water lines or piping
• Filters
• Water pump
• Water heater
• Faucet
• Water heater bypass valves and low point drains.
What are the two things that are needed for any water distribution system to function properly?
• A source of potable water.
• A way of providing pressure to force the water through the system.
Freshwater can be obtained from what two sources?
• A podible water storage tank ( fresh tank)
• A city water connection
What does a freshwater tank ensure?
It ensures there is an adequate supply of potable water.
What is a freshwater tank made of?
It is commonly made of polyethylene plastic. ( But may be made of ABS if listed for potable water use )
How is a freshwater tank filled?
It is filled through a gravity water fill hose or through a city water connection.
What are the 2 types freshwater tanks come in?
• Pressurized
• Non pressurized
What type of freshwater tank do most current RVs use?
Most current RVs use polyethylene non pressurized tanks.
What is the typical shape of pressurized tanks?
Pressurized tanks are typically round in shape.
What are pressurized tanks made of?
Galvanized metal
How do pressurized tanks move water through the potable water distribution system?
With air pressure
How is air pressure maintained in a pressurized tank?
It is maintained by a 12 volt compressor or through a schrader valve.
How do you check a pressurized tank for air leaks?
Use soapy water
If a leaking galvanized tank is replaced with a plastic tank, what do you need to remove and install in its place?
You need to remove the air compressor and install a demand pump in its place
What are non pressurized tanks usually made of?
They are usually made of polyethylene plastic but can be made of ABS if listed for potable water.
What tool is used to friction weld a fitting and a tank together?
A router and a specialized spin fitting bit
What adhesive is used to install fittings on an ABS tank?
Solvent cement
How do you repair damage to a non pressurized polyethylene tank?
A polyethylene tank can be repaired by plastic welding.
What must a freshwater tank be to ensure it remains at atmosphere pressure while filling or draining?
It must be vented
Where must the drain fitting be placed on a fresh water tank?
It must be placed at the lowest point. possible to allow draining by gravity.
What must you do to polyethylene tanks before you use plastic welding to repair a crack?
You need to stop drill the tank before repairing the crack.
What are the 4 common types of plastic piping used for water distribution?
• Polyvinyl chloride (PVC)
• Chlorinated polyvinyl chloride (CPVC)
• Polybutylene ( PB or Poly-B)
• Polyethylene cross-link (PEX)
Of the 4 common types of plastic piping used for water distribution, what is the most common type used in current RVs?
PEX is the most common type used
What type of water line may be used in order RVs or highend motorhomes?
Copper water lines
What type of fittings can PEX tubing use?
Plastic or Brass
Are Poly-B and PEX crimp rings interchangeable?
No
Are PB to PEX transition fittings available?
Yes
What type of cinch rings can PEX connections be installed with?
Steel cinch rings or solid copper rings.
However, the tools to install them are different.
What colors is PEX tubing available in?
It is available in red and blue to identify hot and cold lines. As well as clear or white
How are CPVC and PVC fittings assembled?
They are assembled by using plastic pipe cement or solvent, which melts the plastic to join the pieces together.
What are the steps for assembling CPVC and PVC pipes and fittings with solvent cement?
• Clean and deburr the pipe fitting
• Dry fit the piping and make reference marks
• Disassemble the piping and brush primer on both pieces
• Once the primer has fully dried, apply the solvent cement to both pieces
• Immediately insert the pipe into the fitting and rotate slightly
What should be kept to a minimum when installing distribution piping?
90° elbows
What degree of flare connections are used when copper lines are repaired or replaced with new copper tubing?
45° flare connections
Sealants must be what if listed for potable water?
They must be non toxic
What do filters, filter out?
They filter out particles like bacteria, mold, sediment, and chemicals that may be harmful or effect the water’s taste and smell.
What are inline strainers designed to capture?
They are designed to capture dirt, sand and other debris, before it enters the distribution system.
Are inline strainers considered filters?
No
What is the water pump considered in the potable water distribution system?
It is considered the heart of the system.
What is the most common type of water pump?
A reciprocating diaphragm
What does the moving diaphragm do?
It alternately draws in and forces out water
What are the 6 parts of a reciprocating diaphragm water pump?
• Diaphram pump head (Upper housing assembly)
• Inlet
• Outlet
• Pressure switch assembly
• Motor
• 12 Volt Connection
What is the best placement of a water pump for efficiency when installed?
At the bottom level of the fresh tank, however, most diaphragm pumps can draw water from tanks mounted beneath the floor.
What is the preferred mounting position of a water pump?
Horizontal
Where should the motor be if a water pump is mounted vertical?
The motor should be at the top.
What surface should you avoid mounting a pump on?
Metal surfaces
What helps to quiet the noise of a water pump?
A flexible hose at the inlet and outlet helps to quiet the noise.
What should the pump do when you close all faucets and turn on the pump?
The pump should pressure the system and cycle off
When the pump has pressurized the system and cycled off, an open faucet should do what?
Supply a steady stream of water
What does foamy water and sputtering from the faucet usually indicate?
It indicates air in the lines
Is cycling normal with a partially open faucet?
Yes
What should you do if a pump fails to turn on when a faucet is opened?
You should check the pump circuit protection then test all wiring and connections including the ground.
What do multi switch pump controllers open and close?
The ground circuit
What steps do you take if the pump blows the circuit protection?
• Test battery voltage
• Check that the fuse amperge is correct
• Check the actual pump amperage draw
• Bench test the pump, this can be done without removing the pump.
What should you test for if the pump fuse blows immediately?
Test for a short circuit
What are 4 methods of supplying water pressure?
• City water
• Demand pump
• Manual pump
• Air pressure
What does the CSA Z240 state in regards to placement of the city water connection on RVs?
The connection should be on the left side of the RV toward the back of the vehicle or at the rear within 450 MM or 18” of the outside wall.
What is recommended to use when filling a fresh tank from a city water connection?
A water pressure regulator
Where does the CSA Z240 require a backflow preventor (Check Valve).
At the city Water Connection.
What is the demand pump controlled by?
A pressure switch
Where is the demand pump mounted?
Between the fresh tank and the distribution system.