6712SR Refrigerated Sampler
Section 2 Installation/Preparation
2-7
2.3 Suction Line The suction line is the tubing from the sampling point to the
pump intake. The 6712SR uses a 3/8-inch ID suction line of
lengths 3 to 99 feet. Teledyne Isco offers vinyl or Teflon® suction
lines. The Teflon® tubing has a polyethylene jacket to protect it
from kinks and abrasions.
The vinyl line contains a very low parts-per-million level of
phenols. If phenol content affects your sample analysis, use the
Teflon suction line.
When installing the sampler, be sure the vertical distance
between the liquid level and the pump is as small as possible.
2.3.1 Guidelines for
Measuring and Cutting
the Suction Line
• Cut the line to the desired length but use the shortest
length feasible for the installation.
• Cut the line in 1 foot increments. For instance, 4 feet,
not 31/2. If using metric units of measure, cut the line in
increments of 0.1 meter. Do not include the length of the
strainer in the measurement.
2.3.2 Attaching Suction Line
to Pump Tube
Attach the vinyl suction line to the pump tube with the tube cou-
pling. Use the black clamp for the pump tube and the white
clamp for the suction line. Attach the line and tube to the cou-
pling by pushing them onto each end of the coupling. Then
tighten the clamps by squeezing the finger pads together. Loosen
a clamp by twisting it until its teeth disengage.
Attach the Teflon® suction line to the pump tube by inserting the
line into the tube and secure with a suitable clamp.
2.4 Strainers Teledyne Isco offers three styles of strainer that help prevent
solids from clogging the suction line:
•3/8-inch standard weighted polypropylene strainer for
routine and priority pollutant sampling
•3/8-inch stainless steel low flow strainer
• Weighted, CPVC-coated strainer for acidic liquid sources
To select the right strainer for your application, see Table 2-2. To
install the optional low flow strainer in Teflon suction line, heat
the end of the suction line to make it more pliable, then carefully
screw the strainer’s threaded connector into the suction line.
2.4.1 Alternative to Strainers When sampling from high velocity streams with heavy sus-
pended solids, some field investigations suggest that more repre-
sentative samples are obtained without the strainer. Consider
attaching a short piece of thin walled aluminum tubing to the
end of the suction line; anchor the tubing so that the inlet opens
upstream. The aluminum tubing’s thin wall will not disturb the
flow stream, and most sample analyses disregard aluminum
ions. Under most conditions, the pre-sample purge removes any
debris over the tubing entrance.
Attaching Suction Line Tube Coupling