Some tips on using clear pvc pipe and fittings

We have been supplying clear pvc pipe and fittings for some time now at the plastic pipe shop, and so thought it was about time we offered some advice on precautions tat need to be taken when using them. Firstly, it is important to note that clear pvc is not optically clear in the same way as acrylic tubing. The pipes and fittings have a slight grey / blue tinge to them, the opacity and hue of which is dependent on the thickness of plastic and also the curvature of the fitting / pipe. Given this slight and variable opacity / hue, industrial clear pvc pipe is not always suitable for display systems, a use to which it is often put.

Other applications for clear pvc pipe and fittings include those where the process water needs to be observed. Here it should be noted that in many respects, clear pipe is no different to any other pipe. Cut open a process pipe system that has been continually in operation for some tie and the inside of the pipe is rarely the same colour as it was when it was installed. A gradual build up of colour as a result of settled solids, bacterial, fungal and other biological growth, acids and other chemicals in the fluid is common. This discoloration in itself is not usually an issue, however, where there is fouling in the pipe system, it can have a adverse affect on the flow rates through the pipework by increasing friction. The periodic insertion of a clear pipe section into a plastic pipe system, enables the operator to keep an eye on the level of discoloration and solids build up. This in turn, assists them in making decisions when to shut a system down for cleaning and maintenance. Note however that for effective maintenance to be carried out, pipe systems require to have unions fitted at regular intervals, to enable splitting and reassembly of the pipe system.

The primary issue when installing clear pipes into system, comes when those systems are carrying water and are exposed to sunlight. With even a minute amount of nutrient loading in he water, algal build up on the inside of the pipe can be rapid. This then presets two issues. The first is that the algal growth obscures view of the water, and the second is that if let to grow unchecked, the algae can become filamentous and slough off, which may give fouling issues further down the system pipework. Any such pipework, especially if located outside or exposed to a source of sunlight (i.e. a window etc), must be fitted with unions at either end to allow removal for cleaning and, if the system cannot be stopped for such maintenance, a bypass system. Another option is to fit a shroud around the pipe to block the sunlight, however this rather negates or restricts the purpose of having an observable section of pipe.

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