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EXCERPT - Field Testing Backflow Preventers, Instructional Video

let's take a look at a double check

valve backflow prevention assembly which

will be referred to from this point

forward as the DC first I'll introduce

you to the various parts of the DC let's

begin with test number one shutoff

valve number one test number two

check valve number one test number

three check valve number two tests

number four and finally shutoff valve

number two before beginning the

procedure we must complete the

preliminary steps notify identify

inspect and observe now let's begin the

field test procedure

first let's test for the tightness of

check valve number one bleed water

through test to eliminate foreign

material by opening and closing each

test

install appropriate fittings

if test number three is not at the

highest point of the check valve body

then a vertical tube or pipe must be

installed on test number three so

that it rises to the top of the check

valve body

attach bleed off valve arrangement to

test number two and the hoes from

the high side of the field test kit to

the bleed off valve

open test number two

and bleed all air from the field test

kit by opening the high side bleed

needle valve

then close the high side bleed needle

valve

open test number three to fill the

test number three or two above

attached so that the water level is

above the top of the body then close

test number three close number to

shut off valve the field test kit must

be maintained at the same elevation as

the water at test number three

then close number one shutoff valve

you

slowly open test number three after

the reading stabilizes and water stops

running out of test number three or

is no more than a drip the reading

indicated on the field test kit is the

differential pressure across check valve

number one and is to be recorded as such

the reading must be one PSI d or greater

in this case the reading is three point

two PSI d a passing value

close all test open shutoff valve

number one and remove all test equipment

now let's test for the tightness of

check valve number to attach bleed off

valve arrangement to test number

three and hose from the high side of the

field test kit to the bleed off valve

if test number four is not at the

highest point of the check valve body

then a vertical tube or pipe must be

installed on test number four so

that it rises to the top of the check

valve body open test number three

and bleed all air from the field test

kit by opening the high side bleed

needle valve then closing the high side

bleed needle valve open test number

four to fill test number four or

tube if attached so that the water level

is above the check valve body then close

test number four

the field test kit must be maintained at

the same elevation as the water at test

number four

close number one shutoff valve

slowly open test number four

after the reading stabilizes and water

stops running out of test number

four or is no more than a drip the

reading indicated on the field test kit

is the differential pressure across

check valve number two and is to be

recorded as such the reading must be one

PSI d or greater in this case the

reading is two point four PSI d a

passing value

close all test remove all test

equipment remove fittings open shutoff

valve number one then slowly open

shutoff valve number two

the following must be recorded number

one check valve 3.2 psi D number two

check valve 2.4 psi D overall assembly

status pass this concludes the test