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.
What is the voltage of a demand pump?
12 volt DC
Opening a faucet reduces system pressure, causing the pressure switch to close and the pump to do what?
Turn on
What does closing the faucet do?
Closing the faucet builds pressure until the pressure switch opens and the pump turns off.
What does movement of the diaphragm in one direction cause?
It causes a negative pressure to draw water from the tank
What does movement of the diaphragm in the opposite direction create?
It creates a positive pressure to move water through the distribution system.
What does the pump check valve prevent?
It prevents city water pressure from backing up into the fresh tank and holds pump pressure when its turned off.
What psi does the pressure switch close at?
25-28 psi
What psi does the pressure switch open at?
40-50 psi
Are some pressure switches adjustable?
Yes
What does the pump do if there is a large demand on the system?
The pump will run continuously
With low demand what might the pump do?
It might cycle on and off because the pressure builds faster than the demand, which is normal.
What can rapid cycling of the pump indicate?
A restriction in the system
What can cycling while no fixtures are open indicate?
An internal or external leak.
Where are accumulators installed?
Downstream of the demand pump.
What do accumulators do?
They decrease water pulsations and rapid pump cycling
What do accumulators use a cushion of air for?
To absorbed pressure pulsations.
What would accumulators have a rubber bladder or diaphragm for?
To separate the water from the air
An air pocket accumulator must be installed with…
The air chamber at the top and the plumbing connections at the bottom.
What does the air maintain in an accumulator?
Pressure in the system.
As the water flows past the accumulator, the air is slowly depleted and must be replenished by completely draining the system through what?
The low point drains.
Bladder accumulators have a diaphragm separating the air from what?
The water
Although accumulators can be installed in any orientation, what is recommended?
It is recommended to install them with the bladder at the top and connections at the bottom for full draining when winterizing or sanitizing.
Where is air pressure introduced in the accumulator?
Through a Schrader valve
What can installing an accumulator help?
It may help eliminate leaking from the water heater P&T valve.
For the accumulator to function properly. What must there not be at the water heater inlet?
A check valve
What is a single fixture pump?
It is a low volume impeller pump.
Where must a single fixture pump be installed?
As close to the tank as possible and below the tank water level.
Will a Single fixture pump self prime?
No
What might a blown fuse on a single fixture pump indicate.
A stuck impeller
A manuel pump is manually pumped to deliver what to the fixtures?
Water
What are the 2 types of manual pumps?
• Piston type
• Diaphragm type
How does a manuel pump work?
Water is drawn in by moving the handle in one direction and is forced out by moving the handle in the opposite direction.
What stops the water from flowing backwards in a manual pump?
An internal check valve
What can happen to manuel pumps if left dry for extended periods?
Mineral deposits may be left on the seals or the seals may dry out and crack.
Where are air pressure systems usually found on?
Older RVs
Air pressure systems use air compressors or bicycle pumps to pressurize what?
A galvanized metal water tank.
How does an air pressure system work?
The air pressure forces water through the distribution system when a faucet is opened.
When using an air pressure system what should you make sure to do before opening the water fill cap?
Bleed the air pressure from the tank.
If replacing a rusted or damaged metal tank from an air pressure system. With a polyethylene tank, you must replace the compressor with what?
A demand pump.
What do fixtures refer to?
To components where water from the distribution system is used.
What are examples of fixtures in an RV?
• Sinks
•Tubs
•Showers
•Toilets (water closet)
How must fixtures be installed?
As per their listing.
All fixtures, faucets, and traps are required to be accessible for…
Repair or replacement?
Tubs are commonly made of what materials?
ABS plastic or fiberglass
Tubs are identified as either left or right hand by the location of what while facing the tub?
The drain
Where do tubs drain into?
Either the grey or black tank, but they usually drain into the grey tank to reduce the risk of overfilling the black tank
Code requires that the shower surround must extend upward to a height, not less than what?
150mm (6”) below the head
What does a shower compartment consist of?
A shower pan and surround
You can drain grey water into a black tank, but…
You can not drain black watering into a grey tank
What is the most common material used for a lavatory sink?
ABS plastic
Where is the toilet installed in a wet bath?
In the shower pan to save space
A wet bath may also have the vanity sink inside what?
Shower enclosure
What is a water closet commonly called?
A toilet
A water closet is available in what sizes?
Standard height or low profile
What two types of material are toilets made of?
ABS plastic or porcelain
What is the formula for the volume of a cube?
LxWxH= volume of a cube
What is the formula for the volume of a cylinder?
( 3.14xr²)xH= volume of a cylinder
What does code require for RV toilets?
The toilet must be bolted securely to the closet flange and must also be secured to the floor if the toilet design includes this requirement
What holds up better in cold temperatures PVC or ABS plastic?
ABS Plastic
Exterior shower must have a what?
A vacuum breaker to eliminate contamination due to a drop in system pressure
What should you avoid when installing exterior showers?
Avoid cutting frame members or wiring
Always seal the perimeter against what?
Water penetration and damage
What is a spray away port?
An exterior washing or shower faucet with a detachable hose nozzle
Most fixtures are made of what plastic?
ABS plastic
Repairs on fixtures can often be performed using…
ABS cement, plastic welding, or by using a fiberglass patch.
Sanding and repainting may be required
Why is the replacement of the tub and shower enclosure difficult and time consuming
Because the fixture was often installed before the wall was in place
If a water pump cycles excessively with some fixtures, but not all of them, what should you check?
•Check the aerators
•Check the system for cycling by flushing the toilet, as toilets don’t have an aerator.
Restrictions in the distribution plumbing may cause what with the pump?
Excessive cycling
What does backflow prevention mean?
It means preventing liquid from flowing in an undesirable direction. Backflow preventers are either check valves or vacuum breakers
Check valves are required to prevent what?
City water pressure from backing up through the pump.
• They also hold pump pressure when the pump has cycled off.
•CSA Z240 requires the city water to have a check valve
Vacuum breakers stop backflow by letting what into the system?
By letting air into the system and preventing siphoning
Where are vacuum breakers used?
Inside and outside… anywhere cross contamination is possible
When is leaking or dripping water from a vacuum breaker normal?
When the fixtures are turned off
What should you ensure when removing a vacuum breaker and replacing it with a D-spud?
Ensure the D-ring is installed over the shower hose
What does a D-ring do?
It ensures the shower head can not reach a potential source of contamination such as bath water or the sink and toilet
What are pressure gauges used for?
To test the pressure in the distribution system or to test for system leaks
What can using regulated air pressure and a gauge help determine?
If the distribution system has a leak
Air pressure can often be used to test what?
The system without filling it with water, or without de-winterizing.
What are the steps to disinfect a potable water system?
1) Mix 1/4 cup chlorine bleach with 1us gallon of water ( .06 litres of bleach to 3.8 litres of water)
2) Add the mixture to the system at a ratio of 1 gallon of solution to each 15 us gallons of water
3)Pump solution through system
4) Allow the solution to stand for 4 hours, then flush with clean potable water
What should you ensure the system is completely rinsed of after disinfecting the potable water distribution system?
Bleach solution
What is available if the potable water distribution system needs to be refreshed but not disinfected?
Potable water deodorizers are available
What is an Aerator?
A faucet screen that provides a consistent splash free flow of water
What is backflow?
Flow other than the intended direction
What is a backflow preventor?
A device or means to prevent backflow.
What is a branch?
Any part of the piping system other than a riser main or vent stack?
What is a branch vent?
A branch connecting one or more individual vents with a vent stack.
What is a check valve?
A mechanical valve that permits the flow of liquid in only one direction.
What are crimp rings?
Pinch clamps or solid rings used to install fittings into potable water piping.
What is a drain?
A pipe that carries waste or water in a drainage system.
What are fittings?
They connect one pipe to another to extend the pipe or change the flow direction.
Fixture supply
Water supply to a fixture from a main water supply pipe.
What is a horizontal branch?
Lateral drain pipe that receives the discharge from one or more drain fixtures and connects to the main drain.
What is a plumbing fixture?
A receptacle, device, or appliance that is supplied with water or liquid-borne waste and discharges into the drainage system.
What is pump cycling?
The water pump turning on and off.
What is pump priming?
Initial filling of the water pump.
What does potable mean?
It means safe for human consumption.
What is a trap?
A device that provides a liquid seal to prevent the emission of sewer gasses without affecting the flow of wastewater.
What is a water distribution system?
Piping that distributes potable water.
What is a wet vent?
A vent that receives waste other than waste from toilets.
What are 2 things that are needed for any water distribution system to function properly?
• A source of probable water.
• A way of providing pressure to force the water through the potable water system.
What is the formula for finding the volume of a cylinder?
( 3.14pi x r² ) x H
What is the formula for finding the volume of a cube?
LxWxH= volume of a cube
What is a sail switch?
The sail switch senses when the blower motors fan is moving air at the proper speed. If the switch does not sense proper fan speed, the furnace will not fire.
What is a limit switch?
A limit switch is a component of a forced air furnace. That is responsible for turning on the furnace blower once the desired temperature in the furnace has been met. Without a working limit switch, a furnace would not be able to regulate the temperature in conjunction with the thermostat.
