Sample Setup Guide - Calibrating a Pump Using a Film

Sample Setup Guide - Calibrating a Pump Using a Film
Sample Setup Guide
Calibrating a Pump Using a Film Flowmeter
Personal sampling pumps are essential equipment for sampling airborne contaminants. However,
determining airborne concentrations requires accurate knowledge of the volume of air sampled.
Constancy of flow rate and equipment reliability are two important factors that affect air volume.
Built-in rotameters on pumps are not precision instruments and cannot be used to determine
a pump’s flow rate; they provide only an approximation. Flow rate should be measured with
an instrument such as a film flowmeter that bases measurement on the unchanging physical
dimensions of an enclosed volume. A precision rotameter can also be used, but only if its calibration
is traceable to a device such as a film flowmeter. A precision rotameter is capable of maintaining
accuracy with reasonable care and handling. Unlike film flowmeters, precision rotameters require
periodic calibration. This Sample Setup Guide describes Calibrating a Pump Using a Film Flowmeter. For calibrating with
an electronic calibrator, refer to Publication 1366.
Required Equipment
1. An air sampling pump capable of sampling at the
recommended flow rate with the sampling medium in line,
such as:
• SKC Pocket Pump®
• SKC Universal Series (low flow applications require
Cat. No. 224-26 Series Adjustable Low Flow Holders)
• SKC AirChek® Series (low flow applications require
Constant Pressure Controller Cat. No. 224-26-CPC and
a Cat. No. 224-26 Series Adjustable Low Flow Holder)
2. A laboratory air flow calibrator, such as:
• SKC Film Flowmeter Cat. No. 303 or 311 Series
3. A precision timing device
4. The sampling medium specified in the method*
Introduction
The illustrations in this guide show sampling trains using SKC
Universal Series Samplers. To determine the correct flow
rate for the chemical being sampled, refer to the appropriate
analytical method. Check the sampler operating instructions
to ensure that it is capable of sampling at the correct flow rate.
1. Setting Up the Film Flowmeter
Some film flowmeters come with a separate stand or base.
If so, stand the glass tube vertically using the base so that
the rubber squeeze bulb is at the bottom (Figures 1 and 2).
If no base is provided, use lab clamps and a support stand.
Remove the rubber cap from the lower side arm of the glass
tube. Pour film solution into the lower side arm until it fills the
rubber bulb to about 1/4 inch above the upper rim of the bulb.
The solution level should not reach the side arm of the tube.
A pipette can facilitate the filling procedure. Alternatively, pour
5. Any additional equipment specified in the method*
* Refer to the method and to the related Sample Setup Guide for preparing
a sampling train: Pre-filter and Tube 1164, Impingers 1165, Filters
and Cyclones 1166, Single Sorbent Sample Tube 1168, Two Tubes
in Series 1171, Reusable PPI Samplers 1887, or Disposable PPI
Samplers 1888.
Rubber
Tubing
Outlet
(upper
port)
Tygon
Tubing
Sample
Tube
Adjustable
Low Flow
Holder
Film
Flowmeter
Side
Arm
Inlet
Sample
Pump
Figure 1. Portable film flowmeter connected to sorbent tube
sampling train
Publication 1163 Rev 1702
SKC Inc. 724-941-9701
SKC South 434-352-7149
SKC Gulf Coast 281-859-8050
www.skcinc.com
SKC-West 714-992-2780
Calibrating a Pump Using a Film Flowmeter
film solution through the top of the glass tube. Simply remove
the stopper, tilt the tube, and pour gently. When operating the
flowmeter, the cap must remain off the side arm.
2. Setting Up the Calibration Train
Allow the pump to equilibrate from one temperature extreme
to another and to run for 5 minutes before calibrating. Prepare
an appropriate calibration train as specified in the method.
(See the related Sample Setup Guide for preparing a sampling
train.) Ensure the sampler is in the appropriate mode (high
or low flow) for the desired flow rate and that any necessary
flow accessories are in place. With flexible tubing, connect the
outlet of the sampling medium (filter cassette, sorbent tube,
impinger, etc.) to the inlet of the sampler. Connect the inlet
of the sampling medium to the outlet (upper port) of the film
flowmeter (Figures 1 and 2).
Collar
Clip
Filter
Cassette
Holder
Cyclone/Filter
Cassette Assembly
Outlet
(upper
port)
Sample
Pump
Tygon
Tubing
Flowmeter
Inlet
Flow rate = volume bubble travels (ml or L)
time it took to travel (min)
Using the flow adjust control on the sampler, increase or
decrease the flow rate until it approximates the intended
flow rate as specified in the sampling method. Several
measurements and adjustments may be needed until the
desired flow rate is achieved. It is not necessary to exactly
match the flow rate called for in the method.
4. Determining the Flow Rate
Once the desired flow rate has been achieved, measure the
flow rate at least three more times using the same procedure.
Do not adjust the sampler’s flow adjust control this time.
Average the results. Record this averaged value as the presample flow rate.
5. Sampling
When ready to start sampling, set up a new train identical
to the one used to measure and calibrate the flow. Use a
new sampling medium of the same type. Do not discard the
sampling medium that was used to calibrate the flow; it will
be used to calibrate the flow again when sampling has been
completed. Attach the sampling medium to a worker’s collar
and the sampler to the worker’s belt. Activate the sampler
and note the start time.
Rubber
Tubing
Calibration
Adapter
determine the time it takes for a single soap film to travel from
one volume line to another. This travel time, together with
the volume delineated on the tube, represents the flow rate:
Side
Arm
6. After Sampling
At the end of the sampling period, turn off the sampler and
note the ending time. Remove the sampling medium, seal
it appropriately, and record pertinent sampling information.
Figure 2. Portable film flowmeter connected to an aluminum
cyclone sampling train (with a calibration adapter and
filter cassette holder in place)
3. Calibrating the Flow
Remove the rubber cap from the lower side arm of the
flowmeter. Turn on the sampler. While the sampler is
operating, repeatedly squeeze the rubber bulb at the base
of the glass flowmeter tube until a flat soap bubble (film)
enters the tube and rises up the column. Introduce several
bubbles into the tube to wet its interior so that the soap film
successfully travels the entire length of the tube. Observe the
soap film as it passes the volume lines marked on the glass
tube. Using a stopwatch or other precision timing device,
7. Rechecking the Flow
Reattach the sampling medium originally used to calibrate
the flow rate of the sampler. If it is not available, use new
medium. Using the flowmeter, measure the flow rate following
the directions outlined in Step 3. Record this averaged value
as the post-sample flow rate. Compare the pre-sample and
post-sample flow rates to ensure that the two rates do not
differ by more than 5%. Report the average of the pre-sample
and post-sample flow rates to the laboratory along with other
relevant sampling data.
Copyright 1996 - 2017
Notice: This publication is intended for general information only and should not be used as a substitute for reviewing applicable government regulations, equipment operating instructions, or legal standards. The
information contained in this document should not be construed as legal advice or opinion nor as a final authority on legal or regulatory procedures.
Publication 1163 Rev 1702
SKC Inc. 724-941-9701
SKC South 434-352-7149
SKC Gulf Coast 281-859-8050
www.skcinc.com
SKC-West 714-992-2780
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement