11
3.4.4 Quartz Sleeve
The UV lamp is enclosed by a quartz sleeve made of GE Type 214 or equivalent clear
fused silica quartz.
Mineral deposits will form on the quartz, which inhibit the amount of light that can reach
the water. The sleeve must be manually cleaned on a regular basis using a mineral acid
such as a calcium, lime, and rust remover.
3.5 UV Sensor
Many factors influence a system’s level of UV disinfection. Some of these factors
include water quality (primarily UVT), lamp output, and quartz sleeve fouling. Rather
than base set-points on any one of these factors, alarm set-points are based on the
quantity of light that actually reaches the sensor. In this way, the UV sensor detects
when the water is no longer being purified properly as a result of change in any
influential factor. VIQUA’s UV sensors reliably detect low UV output and identify the
need for maintenance.
3.5.1 Sensor Response Curve
The sensor’s photodiode detects the emitted germicidal 253.7 nm wavelength.
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
1E-8
1E-7
1E-6
1E-5
1E-4
1E-3
1E-2
1E-1
1E+0
200 250 300 350 400 450 500
Linear Spectral Response, S (A/W)
Logarithmic Spectral Response, S (A/W)
Wavelength, λ (nm)
Logarithmic
Linear
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