Chances are pipelines and vessels are too dark for level detection and to view important stages of a process through a sight glass. Flashlights cannot supply sufficient lighting, and may cause a glare on the sight glass, making visual inspection virtually impossible. If the view port is small, there may not even be enough room to combine viewing and lighting. Illumination may be supplied by adding lights (also called “luminaires”) on sight glasses.
When deciding upon a proper light for an application, be sure to consider all of the properties of the light. The size, weight, voltage, wattage, materials of construction, mounting configuration, and light pattern are all very important factors.
How to Know What Wattage Light the Application Requires
The wattage of the bulb you select should be based on the distance of the bulb from the target. The following figure shows the maximum recommended distance for bulbs of different wattages.
The brightness of a light can be measured in lumens. However, because process lighting is focused with a reflector, a better unit of measure is the foot-candle, which measures reflected light rather than direct light. The shape of the reflector and its position in relationship to the bulb affects how wide or narrow the beam will be.
Recommended Maximum Distance
Lights are available in many different sizes and options. If the light needs to be installed in a hazardous area, explosion proof lights are also available. If a port is too small to utilize a standard light, try a fiber optic light – it can fit even the smallest of ports. Cameras, remote electronic timers, pneumatic timers, and pushbutton switches are also available as accessories.
Lights use different mounting configurations, from a “half-moon” type designed to fit a weld-on sight port to the latest sleek sanitary design where the light fits directly into a sanitary fitting for one-piece mounting right onto the ferrule. For existing sight ports, some lights are made to mount easily onto the cover flange. Often, the construction of the light interferes with the design of an existing port. Special ports require special mounting – ask your vendor to design a mounting configuration to suit your needs.