Technical data

250 ml Pyrex beaker
500-ml graduated glass cylinder
Two jug-type glass storage bottles, gal, with screw
caps
Hydrometer, 1.60 - 1.80 specific gravity
Pyrex watch glass, 75 - 90mm dia
Nalgene polyethylene wash bottles, 250 ml
Bar magnet
Spatula, stainless steel
Glass stirring rods, 10 inch
Neoprene gloves, size as required such as: Playtex
neoprene.
NOTE
Laboratory equipment may be purchased
from national laboratory supply firms
such as Fisher Scientific, VWR Scientific,
Curtin Matheson Scientific, or from local
laboratory supply firms found in most
large cities.
2.11.12.2 Sampling Procedure. Collect approximately
two liters of used media, preferably from the blast pot or
hose.
2.11.12.2.1 Used Media. The best representative
sample is obtained by collecting media directly from the blast
nozzle; but if this is not feasible, collect the sample from
media hoppers located after separation equipment in recov-
ery/reclamation system.
2.11.12.3 Contamination Test Procedure. Proceed as
follows
a. Ensure all glassware is clean and dry.
Keep solvents away from heat and open flame.
Keep containers closed. Use only with adequate
ventilation. Avoid prolonged or repeated contact
with skin and swallowing.
b. Prepare a mixture of 95% by volume Perfluorohexane
(SG 1.68), 3M Company PN PF-5060TM, and 5% by
volume ASTM D1836 N-Hexane (SG 0.66). To make
mixing easier, pour the N-Hexane into the container
first, and then add the PF-5060TM fluid. Using a
hydrometer, measure the specific gravity (SG) of the
mixture to ensure it is within the range of 1.60 to 1.66.
If the SG is below 1.60 add a small amount of
PF-5060TM until the SG is within range; if the SG is
above 1.66, add very small amounts of N-Hexane until
the SG is within range. This fluid mixture is to be used
in testing for high density particle contamination of used
media. The SG of this fluid mixture is high enough to
float the light plastic media particles while allowing
high density particles to separate and settle out. A
quantity of this test fluid mix may be prepared in
advance and stored until needed in small necked, tightly
capped bottles marked with the value of the SG of the
fluid they contain.
c. Add approximately 300-350 ml (bulk dry volume) of
sample media to 500 ml beaker. Weigh beaker and
media to the nearest tenth gram (0.1 gm) and record
(Weight #1) gross weight. Pour media into 500 ml
separatory funnel (stopcock closed) and ensure there is
no spillage. Obtain tare weight of 500 ml beaker and
record (Weight #2) to the nearest tenth gram (0.1 gm).
d. Add the fluid to separatory funnel leaving some air
space in the funnel for ease of agitation. Swirl the
mixture. A swirling motion is better than shaking to
reduce entrainment of air and suspension of particles
due to energy of motion of the moving fluid. Media
samples may contain some dust-sized particles, which
may be suspended in the fluid after agitation and adhere
to the sides. Tapping the side of the funnel should
dislodge any particles adhering to the sides. Place the
separatory funnel on the rod stand using the holding
ring. Allow 10 minutes for the suspended dust to settle
or rise. Higher density particles will accumulate in the
bottom of the separatory funnel on top of the stopcock.
e. Fold the filter paper in a standard filter fold and place it
in a funnel. Position the funnel in a holding ring on the
rod stand beneath the separatory funnel and place a
beaker beneath this funnel to catch the test fluid. Use
short duration opening of stopcock in order to drain
higher density particles settled out in the bottom of
separatory funnel (on top of stopcock) into filter funnel.
TO 1-1-8
2-24