I did take a few other exceptions to this specification. For example, a PVC corporation stop and nozzle assembly is called for. As far as I’m aware, the corp stops available incorporate a metal safety cable attached to a metal valve (usually bronze, since there is no chemical contact), to insure that the nozzle is safely retained should a blow-out occur. PVC is not that strong a material, so it is usually not used. A bit of fume corrosion to a bronze valve is an acceptable trade-off. Another example of an exception would be that a teflon-on-teflon pump head is called for, even though the plumbing is PVC. Given teflon’s notorious reputation for cold flow, teflon-on teflon is just too slippery to make a good check valve seal. I went with a PVC pump head with teflon seal rings and a teflon diaphragm. Any other exceptions I made were small, based on actually available products, or done to maintain system integrity – so that the whole package "hangs" together.

The Touchscreen will display its two 4-20 mA inputs, the 4-20 mA output to the pump, the Digi-Pulse feedback signal to confirm actual pump strokes, chemical flow in ml/min and total ml’s since last reset (Please specify if you’d like other units, like gallons per hour), and whether there is a no-flow or low level condition. If you have any other ideas, please let us know.

Generally, layout drawings and wiring diagrams are made available after a contract is awarded. Manufacturer’s literature for non-customized components is of course available. Please let me know what you’d like us to provide. Thanks for the opportunity to bid on this – please call if you’ve any questions.

Tim

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