horiba HU-200TB-W SS-120-W, Инструкция по эксплуатации

Страница: 28 / 109

Installation
16
Sampling

sampling pump

Types of sampling pump
For a sampling pump, select a submerged centrifugal pump that is free from rusting.
Tip
Some types of pump, such as cascade-type pumps, diaphragm-type pumps, piston pumps, tube
pumps, and gear pumps, are not suitable for use because the discharge pressure rises rapidly when
the pump outlet is closed. If any of these pumps is used, be sure to provide a pressure relief valve.

Selection of submerged pumps

If you like to use submerged pump, be sure to select a pump with a power that the
discharge pressure is enough for the delivery to the height of the detector and the flow
rate is enough for the sampling flow rate.

If sample includes solids which deposit as a sediment increase flow rate to prevent
adhesion of soil to the inner wall of piping.
Tip

It might be a effective way that a large flow rate of sample is carried to a position near the
detector and the sample to the detector is branched at the position.

It might be an another way that a large flow rate of sample is carried to a overflow tank and the
falling sample from the overflow tank is provided to the detector.

When the pump is stopped, the sampling piping becomes empty due to reverse flow. To
prevent this, provide a check valve.

Flow rate of sample water

The flow rate of the sample water of tap water, etc., can be reduced by switching to the in-
line measurement. In this case, throttle the flow rate on the outlet side of the detector and
perform measurements while the detector is pressurized. This makes it possible to
mitigate the influence of air bubbles. The flow rate can be decreased to a range from 0.5
L/min to 1 L/min.

When easily precipitating sample water is measured, set the flow rate to approximately 20
L/min.
Tip
If anything that tangles easily, such as hair, is contained in the sample water, install a rough filter in
the sampling line.

Uniformity in turbidities of sample water
The turbidities of sample waters must be uniform to some degree. If the SS does not disperse
but clumps together and forms a fluke, throttle the outlet of the pump to increase the pump
passage time, so that the sample water can be agitated by the blade of the sampling pump.