K-Patents PR-21-S - Manual (Page 16)

10 PR-21-S instruction manual
2.2 Mounting
2.2.1 Sensor location
The sensor is delivered with mounting guides attached, Figure 2.3 and Figure 2.4. The
sensor is designed for being installed directly in a process line. If the sensor is located
out of doors, some basic protection against direct exposure to sunlight and rain should
be provided.
Air-cooling
Normally, draught and natural convection provide sufficient air cooling. Criteria for
efficient air-cooling:
1. The sensor should be mounted with the main axis horizontal, Figure 2.4
2. There must be no obstacles for air to flow around the sensor head.
3. The sensor cover should not be exposed to high temperature radiation.
If the ambient temperature is higher than 45°C (113°F) the air-cooling should be im-
proved by blowing pressurized air against the sensor cover. This is also recommended
when the process temperature is above 110°C (230°F) when the ambient temperature
is above 35°C (95°F). The pressurized air can be supplied by the ventilation system.
If no air is available it is possible to wrap a copper coil for cooling water around the
sensor head cover.
Process flow conditions
The sensor is designed to make the prism self-cleaning. To ensure a representative
sample and also prism cleaning action, a good process flow should be directed against
the prism surface. A flow velocity above 1.5 m/s (5 ft/s) is recommended. For lower
velocities prism wash (Section 4) should be considered. Flow velocity is calculated
from v[m/s] = 21.2 * Flow[lit/min]/d²[mm]; v[m/s] = 0.125 * Flow[Gpm]/d²[in].
Accumulation of sediment or of gas bubbles should be prevented.
If the process pipe vibrates, support the pipe.