Evoqua WALLACE & TIERNAN DEOX/2000, Инструкция по эксплуатации

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W3T331759 / WT.050.585.003.UE.IM.1014 18
MICRO/2000® AND DEOX/2000® MODULE
A well-designed sampling system minimizes response time, prevents
fouling of the sample line plumbing and the analyser, and provides a
fully developed turbulent flow to the analyser.
Response time is minimized by locating the analyser close to the point of
sample take-off and by designing for a moderately high flow velocity in
the sample line, 1.5 m/s (5 ft/sec). Flow velocity also helps in reducing
sample line deposits.
Plastic pipe or tubing (PVC, ABS, or polyethylene) is preferred for sample
line plumbing due to its corrosion resistance, lack of residual demand,
and smooth surface finish, which resists deposits. Never use copper pipe
or tubing. Avoid the use of metal lines or fittings.
Sample plumbing pipe (or tubing) size is a function of the available
pressure at the sample point (or sample pump discharge) along with the
sample line length and flow velocity required.
2.3.5.1 Potable Water
Four characteristics typical of potable water are that, generally, it
is low in particulates, it is available at reasonably high pressure
>1 bar (>15 psi), its use should be minimized, and the wetside may be mounted
within 7.5m (25 feet) of the sample point. In such applications, the sample
may be run through 6mm (¼-inch) pipe or tubing and the bypass flow on
the Y-strainer may be shut. It should be opened only intermittently to flush
the strainer element and sample line. Then only approximately 500 ml/min
of the sample is required, which is the internal analyser sample requirement.
2.3.5.2 Wastewater
Frequently, wastewater is high in particulates and biological growth potential.
The sample is taken from open channel flow, with no pressure available
at the sample point. Additionally, the wetside must frequently be mounted
a significant distance from the sample point (inside and protected from
weather). Here, a sample pump is required and the Y-strainer bypass flow
valve should be open to allow continuous flushing of the strainer element.
A high flow, low pressure, open impeller type pump works well in this
environment. Typical systems use ½-inch pipe or tubing that bypasses
7.6l/m (2 US gpm) through the Y-strainer or 3/4-inch pipe that bypasses
19l/m (5 US gpm). This results in a flow velocity of about 1.2m/s (4 feet/s)
and a pressure drop of about 0.3 bar (4 psi) per 30m (100 ft) of sample line.
Wastewater will frequently exhibit high biological growth potential; therefore,
the sample line may need to be treated with a cleaning (biocidal) agent
(typically chlorine) to inhibit growth in the sample line. Biological growth
may clog fittings in the sample line or wetside and consume (process) chlorine