HF scientific MicroTOL Online Turbidimeter old series- 0-1000 NTU - Manual (Page 13)

MICRO TOL (12/04)
Rev. 2.7 7
3.2 Plumbing
The recommended plumbing for the instrument is shown in Figure 4. The instrument is
designed to require very little head pressure to operate. The flow through cuvette is rated
for a flow of 100ml/min. – 6 liters/min. (0.26-1.5 Gal/min), and a maximum pressure of
414 kPa (60 PSI.). The maximum allowable fluid temperature is 50°C (122°F).
Figure 4: Recommended Plumbing for the Instrument
The instrument is equipped to be plumbed using 4.75 mm (3/16”) ID, 8 mm (5/16”) OD
flexible tubing. Opaque tubing should be used if the tubing will be exposed to sunlight,
to prevent algae growth.
In figure 4, there are two flow devices shown. The one on the input side is a shutoff
clamp used during cuvette maintenance. The other device is a backpressure valve.
Backpressure may be required to prevent air from coming out of solution, which may be
observed as tiny air bubbles.
The instrument is equipped with an internal foot valve, which opens in case the flow
through cuvette ruptures, to prevent damage to the sensor. The stem of the emergency
drain can be connected to a 16 mm (5/8”) tube (not supplied) to direct the flow of water
to a convenient drain. Keep the length of this emergency drain to a minimum.
Note: The foot valve system can handle up to 1.5 liters per minute (0.4 gallon per minute).
Flow rates higher than this will cause the instrument to flood in the event of a
ruptured cuvette.