Popular Mechanics - USA (2022-05 & 2022-06)

HOW A PRESSURE WASHER WORKS

1

Select the right noz-

zle for the job. (See

chart on the next page.)

2

Keep the nozzle an

appropriate distance

from the work

surface to avoid damage.

If possible, experiment

on an inconspicuous area

before moving to more

visible ones. The closer you

get, the more the water jet

will tend to cut, not clean.

3

Keep moving. As with

getting too close to

what you’re cleaning,

the longer you stay in one

place or the slower you

move the nozzle, the more

likely it is to cause damage.

4

Avoid electricals.

Don’t wash light

fixtures, outlet recep-

tacles or their boxes,

keypads for garage door

openers, switch boxes, the

attachment point for the

home’s electrical service

cable, the electrical meter,

digital cameras, doorbells,

or the cabinet for backup

generators. High-pressure

water can knock loose

electricals or drive water

inside, creating the poten-

tial for corrosion and

electrical failure.

5

Avoid insulated glass

windows and doors.

You might damage the

airtight seal surrounding

each pane of glass.

6

Be wary of things that

could be knocked over

or easily torn fabrics.

Treat tables, chairs, barbe-

cue grills, fabric awnings,

and shade sails with care.

First, Do

Water enters the pressure washer via No Harm

a garden hose (a) and moves through

a pump, which consists of a series of

two or three plungers (b) arranged in

a line or a circle. The plungers are pow-

ered by an output shaft on the engine or

from a motor. Each plunger boosts the

water pressure sequentially, one feeding

higher pressure water to the plunger next

in line. The last pulse of high-pressure

water exits the pump. The water moves

through a component called the unloader

(c). This component unloads water if it

gets too hot because the gun’s trigger is

off. Next, the water travels down the hose

to the gun (d). When you pull the gun’s

trigger, you send a series of high-pressure

pulses of water out the nozzle.

“It’s important to understand that

the pump produces cleaning and rins-

ing efficiencies with high-velocity

water pulsations,” says Vince Morabit, a

mechanical engineer who’s designed and

developed outdoor power equipment from

pumps to chainsaws since the early 1960s.

“Think of it this way: The kinetic energ y

in that pulse of water is like a chisel being

struck repeatedly by a hammer.”

And since residential pressure wash-

ers also dispense cleaner, either out of a

built-in tank (e) or by siphoning it out of

a bucket, they clean via mechanical and

chemical means.

You apply the cleaner and then rinse

the surface. The cycle is always the same:

clean, rinse, repeat.

“The cleaning agent you use is as

important as the pressure washer itself,”

says Morabit. By selecting the right one,

you rely less on the pressure washer’s force

and more on the gentle removal of grime

by the chemical action of the cleaner.

a

d

b

e

GAS VS. ELECTRIC:

HOW TO CHOOSE

GAS

BUY IF YOU NEED: Power, a

wide selection of sizes and types.

AVOID IF: You don’t like a

lot of noise or doing engine

maintenance.

ELECTRIC

BUY IF YOU NEED: Quiet

operation, only enough power

for small jobs, low maintenance.

AVOID IF: You do a lot of heavy

cleaning.

c

May/June 2022 77

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