Walchem EZ Series Instruction Manual - 1.0 Introduction
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1.0 INTRODUCTION
1.1 Safety and Caution Notes
Always wear protective clothing, eye protection and gloves before working on or near a metering pump. Follow
all recommendations of the supplier of the solution being pumped. Refer to the MSDS from the solution supplier
for additional precautions.
Walchem EZ Series metering pumps should be installed where ambient temperatures do not exceed 122°F
(50°C) or do not fall below 32°F (0°C). Pumps should always be shielded from direct exposure to the elements.
Black UV resistant tubing should be used if the tubing is exposed to strong UV radiation (sunlight/lamps).
WARNING Risk of electrical shock!
This pump is supplied with a grounding conductor and grounding-type
attachment plug. To reduce the risk of electrical shock, be certain that it is connected only to a properly
grounded, grounding type receptacle with ratings conforming to the data on the pump data plate. Prior to
performing any maintenance on a pump, disconnect the pump from the electrical power source.
Plumbing Precautions
All tubing must be securely attached to the fittings prior to starting the pump (see Section 2.3). Only use
Walchem tubing with your pump. Tubing should be shielded to prevent possible injury in case of rupture or
damage. UV resistant tubing should be used if the tubing is exposed to UV light. Always adhere to local
plumbing codes and requirements. Be sure that the installation does not constitute a cross connection. Walchem
is not responsible for improper installations. Prior to performing any maintenance on a pump, depressurize the
discharge tubing.
In flooded suction, pumping downhill, or pumping into little or no system pressure installations, a back
pressure/anti-syphon device must be installed to prevent over-pumping or siphoning. Contact your Walchem
distributor for additional information.
Solution Compatibility
CAUTION! This pump has been evaluated for use with water only. The suitability of this pump for use with
liquids other than water (such as acids or alkalines) is the responsibility of the user. For liquids other than
water, select the best-suited liquid end material combination using a chemical compatibility chart.
1.2 Principle of Operation
The EZ series electronic metering pumps consist of a pump unit, a drive unit, and a control unit. The drive unit is an
electromagnetic solenoid. When the solenoid coil is energized by the control unit the armature shaft moves forward
due to the magnetic force of the solenoid. The shaft is attached to a PTFE faced diaphragm which is part of the pump
unit. The diaphragm is forced into the pump head cavity decreasing volume and increasing pressure which forces liquid
in the pump head out through the discharge check valves. When the solenoid coil is de-energized, a spring returns the
armature to its starting position. This action pulls the diaphragm out of the head cavity increasing volume and decreasing
pressure. Atmospheric pressure then pushes liquid from the supply tank through the suction check valves to refill the
pump head.