Adjustment shall be by means of readily accessible dial knobs, one for changing stroke length and the other for changing stroke frequency. Both knobs are to be located opposite the liquid handling end. Control of Series E7 metering pump shall be selectable between internal and external pulsing by means of a stroke frequency knob. When this knob is rotated to its fully counter-clockwise position, the external pulse mode shall be engaged.
Drive
The pump drive shall be totally enclosed with no exposed moving parts. Pump drives shall be UL listed Class I, Groups C and D and Class II, Division 1, Groups E, F and G. Solid state electronic pulser shall be fully encapsulated with no exposed printed circuit etch and with quick connect terminals at least 3/16" (4.75 mm) wide. Electronics shall be housed in chemical resistant enclosure at the rear of the pump for maximum protection against chemical spillage. Average electrical power consumption shall not exceed 44 watt hours per hour under full speed and maximum pressure conditions.
Automatic Pressure Relief
To eliminate need for pressure relief valve, Liquifram shall automatically stop pulsating when discharge pressure exceeds pump pressure rating by not more than 35%.
Material
Chemical metering pump housing shall be of urethane painted cast aluminum and urethane painted cast iron. All exposed fasteners shall be stainless steel. Chemical metering pump valves shall be ball type, with ceramic balls1 . Valve seat and seal ring shall be renewable by replacing only the combination seat-seal ring2 or cartridge valve assembly. Pump head shall be of transparent acrylic3 material capable of resisting the pumped chemical. Fittings and connections at pump head shall be PVC.
Check Valve And Tubing
A total of 16 ft (4.9 m) of polyethylene tubing5 shall be provided per pump complete with compressing connections. A foot valve with integral one piece strainer shall be provided for the suction line, and an injection check/back pressure6 valve with 1/2" NPT male connection for the injection point. The injection check valve shall incorporate a dilating orifice which inhibits accumulation of crystalline deposits.
