|
DEFINITION: Often called PVC glue,
the more proper term is solvent cement. It consists of solvents that
attack and soften the surface of the PVC that it is applied to, and
resins that serve as a filler. When applied properly, the
solvent will evaporate or "flash off" leaving a single mass of
conduit/fitting/and resin to form the joint.
STANDARDS: In the past, the electrical
industry has had no standards set for cements, for use on pvc
conduit. We have always followed the standards set forth by
ASTM D-2564. NEMA has recently
proposed this ASTM as a standard for the
electrical industry. ASTM D-2564 sets
forth standards for the types of cements to be used on
different sizes and schedules of PVC pipe. All United
Elchem cements meet or exceed this standard, and the
conduit sizes and schedules we reference come directly from this
standard.
NOTE !!! Not all conduit
manufacturers, fitting manufacturers, or pvc cement suppliers adhere
to these standards. The ASTM standard requires listing of the
applicable conduit sizes on the can. Just printing
ASTM-D2564 without listing the specific conduit sizes is
not in compliance with the standard! If you purchased a car that was
tested on the INDIANAPOLIS SPEEDWAY it doesn't mean it will
handle at 180 MPH. Many market a regular bodied cement instead of
medium bodied cement for use on all sizes of
conduit.
BODY: PVC cements come in
Regular(sometimes called light), Medium, and Heavy bodies. This
refers primarily to the mixture of solvents and resins, and is
clearly visible in the thickness of the product. Heavy body is
not generally used in the electrical industry as it is primarily
designed for pipe sizes from 6-12". As a general point of reference
based on standards from ASTM D-2564, the
following application data should be followed: REGULAR
Bodied cements are rated for use on PVC pipe sizes up to
2-4", Schedule 40 only, dependent on the manufacturer.
MEDIUM Bodied cements are for use on all pipe sizes
through 6" including Schedule 80. FOR
ELECTRICAL APPLICATIONS OUR RECOMMENDATION IS ALWAYS A
MEDIUM BODIED PRODUCT.
CLEAR OR GRAY?: In today's PVC
cements, there is virtually no difference other than the color of
the pvc resin used in the product. Many of the earlier cements
were gray, but have decreased in popularity over the years.
Gray generally costs a bit more than clear as the gray resins are
slightly more expensive.
SHELF LIFE: United Elchem PVC
cements offer a 3 year shelf life-The longest in the industry. Some
manufacturers offer 1-2 years, and in other cases it is non
existent. We date code each can and carton for reference, and
maintain a manufacturing sample to check against any product where a
complaint may be made.
PRODUCT DATE
CODES: EACH CAN OF PRODUCT FROM UNITED ELCHEM HAS A
CODE ON THE BOTTOM OF THE CAN THAT DESIGNATES THE EXACT TIME IT WAS
MANUFACTURED. ( KINDA LIKE A BUDWEISER BORN ON
DATE) BELOW IS AN EXAMPLE WITH AN EXPLANATION OF THE
CODES.
8G0713D
YEAR(8=98)
MONTH(G=JULY) DATE(07=7th OF
MONTH)
BATCH # SHIFT
# MFG. PLANT
LOCATION
COLD WEATHER APPLICATION: Most
product complaints occur in cold weather, most commonly that a joint
will not set up, and it pulls apart. All standard solvent cements
are made with solvents designed to evaporate or flash off at
temperatures down to 40 degrees. Some manufacturers claim a 32
degree work temperature, but they are being aggressive. The solvent
simply looses its ability to evaporate and the joint can't set up.
Many Regular Bodied Cements start to have set up problems in the mid
40 degree range. POLARWELD uses special
solvents that will continue to flash off down to 0 degrees, although
the set up time increases as the temperature drops.
WET APPLICATION: Just a small
amount of moisture on the conduit will render most PVC cements
useless. The solvent simply cannot penetrate the water to attack and
soften the PVC. PLUMB-TITE uses a special
solvent that can cut through the moisture and make a solid joint
even in the worst of conditions.
USE OF PRIMERS: There is no
electrical standard for primers. A primer helps clean the PVC,
and the solvents in it pre-soften the plastic prior to the
application of the cement. Using a primer will make a better joint
than one made with a pvc cement only. When using a primer, do not
allow it to dry, but apply the cement directly on top of the wet
primer. Most electrical conduit joints can be made without a
primer if the conduit and fitting are clean and dry.
CEMENTS FROM CONDUIT
MANUFACTURERS: Most conduit and fitting manufacturers
offer a cement with their product line. It is a buy out item for
them, and is sold as an accessory to round out their line. In most
cases, the prices are sky high, and in many cases the products
are not rated to the ASTM standard. Read the can label. Some
of the fitting people are selling a regular bodied cement as a
standard product, and it does have size limitations.
USAGE GUIDELINES: Per quart,
anticipate the following number of joints can be made.
1/2"=300, 3/4"=200, 1"=125, 1 /2"=90, 2"=60, 3"=40,
4"=30, 6"=10
| 
