SKC 311 User Manual

Operating Instructions

863 Valley View Road, Eighty Four, PA 15330 USA

Tel: [phone] e-mail: [e-mail]

Soap Film Flowmeter

Cat. No. 311-1000

Assembly

Screw the tripod legs into the base ring. Insert the bulb end of the fl owmeter into the center
hole of the base ring and slide the glass down into the ring until the zero line is approximately
1 1/2 inches above the base ring. Tighten the screws until the O-ring is compressed snugly
against the glass.

Outlet

(upper port)

Flowmeter

inlet (lower

side arm)

Close up of 311 Flowmeter

side arm (inlet)

Rubber

tubing

Preparation

Tip the fl owmeter at an angle and pour a small amount of fi lm solution into the top of the
glass tube so that the liquid runs down the sides. Squeeze the rubber bulb occasionally to
release trapped air and continue adding fi lm solution until the liquid fi lls the bulb and rises
to a level just below the side arm inlet.

To calibrate a sample pump, connect the pump, with the sampling media in line if applicable,
to the appropriate end of the fl owmeter. If the pump draws air, connect it to the rubber tubing
a ached to the rubber stopper (see Figure 1 on reverse side). If the pump blows air, connect it to
the lower side arm of the fl owmeter using rubber tubing. The 311 Laboratory Film Flowmeter
Kit is calibrated to a primary standard ± 2% of the volumes marked on the fl owmeter.

Operation

Turn on the pump. Gently squeeze the rubber bulb to bring the liquid level momentarily above
the sidearm inlet. Bubbles (soap fi lm) will form which travel up the glass tube with the air
fl ow. Repeat until the bubbles travel the length of the tube without breaking.

CAUTION: Do not squeeze the bulb for more than an instant. Vigorous squeezing
may form a froth which makes timing bubbles diffi cult and may cause fi lm solution

to be drawn into the pump.

Use a precision stopwatch to time a single fi lm as it travels between the volume lines marked
on the glass. Start the stopwatch when the fi lm reaches the zero line and stop the stopwatch
when the fi lm reaches the volume line. (It is usually best to form several bubbles 5 to 6 seconds
apart and time the last bubble.) Record the time. Repeat the procedure at least three times
ending at the same volume line and average the results.

Determining the Flow

Calculate the fl ow using the equation:

Flow (ml/min) = x (Volume line used {ml})

60
Time (sec)

Flowmeter

Media

Sample

pump

Pump inlet

outlet

Media

inlet

Inlet

(lower side arm port)

Figure 1.

311 Series Flowmeter in calibration train with vacuum pump

SKC Limited Warranty and Return Policy

SKC products are subject to the SKC Limited Warranty and Return Policy, which provides
SKC’s sole liability and the buyer’s exclusive remedy. To view the complete SKC Limited
Warranty and Return Policy, go to h p://www.skcinc.com/warranty.asp.

Form 3702 Rev 1210