Sears 390.2518 Major Components / Piping, Major Components What They do, Piping in the Well

MAJOR COMPONENTS / PIPING

MAJOR COMPONENTS

AND WHAT THEY DO

NOTICE: Use Teflon tape supplied with the pump for making all

threaded connections to the pump.

Impeller and Jet

Impeller turns with motor shaft, causing water to fly out from its

rim by centrifugal force. Impeller rotation creates a vacuum which

pulls in more water. Part of the water is diverted back to the jet

where it passes through the nozzle and venturi. This creates more

vacuum to draw in more water.

In shallow wells (less than 20 feet deep), the vacuum created at the

pump is enough to pull water to the pump. Therefore, the jet as- sembly is built into the pump.

Horizontal Piping from Well to Pump

On well point installations where the horizontal piping is more

than 25 feet, a check valve should be installed (Figure 3).

When the pump is offset more than 25 feet from the well, hori-

zontal piping should be increased in size to reduce friction losses. Never use offset piping that is smaller than the suction tapping of the pump.

Horizontal Offset Piping Sizes - Shallow Well Jets

1-114"1-1/2"2"

Up to 25 ft. 25 to 50 ft. 50 to 200 ft.

Air Volume Control

The air volume control (AVC) maintains the cushion of air in

Standard tanks.

Pressure	Switch
The pressure	switch provides		automatic		control.
MODEL	NO.	PUMP	STARTS		AT PUMP	STOPS AT
390.2514			40	PSI		60	PSI
390.2518			40	PSI		60	PSI

Tank

The tank serves two functions. It provides a reservoir of water, some of which can be drawn through the house fixture before the

pump must start. It maintains a cushion of air under pressure.

Two types of tanks are available. Captive _ and Standard. No air

volume control is needed with Captive Air* Tanks.

PIPING IN THE WELL

A shallow well jet pump can be installed on a dug well, drilled well or a driven point. SEARS shallow well jet pumps have a built-in check valve. In a dug or cased well, a foot valve and strainer should be installed for easy priming. It should be 5 to 10 feet below the lowest level to which the water will drop while pump is operating (pumping level) (Figure 1).

The strainer should not be too close to the bottom, or sediment may clog it. Before installing foot valve, check to see that it works freely.

When using a foot valve, a priming tee and plug must he included (Figure 2).

Be sure the vertical distance (lift) from the priming level to pump is not over 20 feet, if the pump is over well This will be less if pump is offset from the well. Both figures are for sea level. The maximum lift of any pump decreases with the elevation above sea level. This decrease is at the rate of 1 foot per 1000 feet of eleva- tion. For example, the lift is 17 feet and your elevation is 3000 feet above sea level. You would then be pumI:Cmg 17 plus 3, or 20 feet. This is still satisfactory for shallow well pumping.

Discharge Pipe Sizes

When the pump is some distance from the house or point of water use, the discharge pipe size should be increased to reduce pressure

losses.

1"1-1/4"1-112"

Upto 25 ft. 25 to 100 ft. 100 to 600 ft.

1-1/4"	WellSeal
	Pipe	._VaVak,e
Plastic Pipe
	PlasticC_CvheC		NOTE:	Chec_
			k	u_e_ i_ hc_
			vabe
			zomel	_pmg =s25
			Steel
	Plastic Pipe		Drive
F			Pipe
5'To10'
Pumping Level	Foot Valve
L	and Strainer
			h. or more.
			Ddve
		--	Coupling
		_=J_	Well Point

DUG OR CASED WELL

DRIVEN POINT

Figure I Figure 3

EMERGENCY POWER

In some areas and with some installations, an emergency power

supply to guard against power failure is a good idea. If you install

an engine-generator set for emergency backup power for your

pump, supply the generator set manufacturer with the nameplate

data from the pump motor. He will then be able to provide a gen-

erator of the correct size to power your pump. Klso, be sure to add Figure 2

the load from any other accessories (such as lights) that may be on the same circuit.