Q. What information is required to select the proper pump?1.Volume of liquid to be dispensed.
2.Properties of liquid such as viscosity, specific gravity and chemical resistance
3.System backpressure.
4.Suction lift if applicable.
5.Options needed such as analog control, pulse control, flow monitoring and timer
Q. What are the primary advantages of a solenoid driven metering pump?The pump drive has only one moving part, the armature shaft. Generally, the less moving parts, the more reliable the pump. Solenoid pumps are very good for low pressure applications and compensation for line voltage fluctuations are excellent.
Application Q. What are the most important considerations when working with metering systems?The most important considerations when working with metering systems are:
A.Discharge pressure
B.Stroke Frequency
C.Suction lift
D.Altitude
E.Chemical compatibility
Q. When discharging to atmosphere, what steps will improve repeatability of dosing?Installing a spring in the discharge valve of the pump gives some improvement, but for the maximum improvement, a backpressure valve should be installed at the end of the line.
Q. What should I adjust the backpressure valve to?1.Never exceed the maximum operating pressure of the pump.
2.When working with a positive displacement metering pump, the discharge must be at least 15 psig higher than the pressure on the suction side of the pump.
Q. To what pressure should the pressure relief valve be set?The pressure relief valve should be adjusted within the range and not to exceed the maximum operating pressure of the pump. The pressure relief valve is designed to prevent an over pressure condition with the pump. For example, if the pump maximum operating pressure is 50 psig, the pressure relief valve should be set at 50 psig. or below to insure proper operation of the pump. Over pressure conditions are the prime reason for pump failure.
Q. How can the suction lift be calculated for liquids other than water?Divide the pumps rated suction lift by the specific gravity of the liquid.
Q. When should flooded suction be used?Flooded suction should be used when:
1.Fluid being pumped out gases.
2.Fluids have high specific gravity.
3.High stroke frequency is needed.
4.The pump is operated in a high altitude region.
5.The application requires a large storage tank where suction lift is impractical.
Q. Can you give me some advice on choosing liquid ends? What are some common problem areas involving chemicals with liquid end and seals that should be avoided?Some of the common problem areas involved with metering pump heads include pumping acids, chlorine, fluorides and hydrogen peroxide. It is difficult to specify exact materials because of the concentration level and the operating temperature. We recommend a PVC head with Viton seals for fluoride applications. Hydrogen Peroxide mixtures can only be used with a PTFE or Stainless Steel head with PTFE seals. Sulfuric acid concentration should be run with a PVC or Noryl head and PTFE seals.
Q. When working with liquids in hydraulic systems, what considerations must be taken into account?The primary considerations are Viscosity, Specific Gravity, Vapor Pressure and Temperature.
Accessories/Options
Q. What is the purpose of the foot valve?The foot valve is comprised of a weight to help hold it straight and vertical in the chemical tank. It is also a check valve to keep a positive direction of flow. This valve also aids in repeatability and priming of the pump. It has a strainer to prevent particles from being drawn into the suction line. Small particles may cut or tear the diaphragm. The foot valve also has a connector set to adapt it to the suction line. The foot valve should be kept off the bottom of the tank and should be mounted in a vertical position. A foot valve is required in most applications using suction lift.
Q. What is the purpose of the injection valve?Injection valves are used to connect the pump discharge line to the point of injection. Injection valves are not to be used as an isolation device or for anti-siphon protection. The injection valve gives a 10 psig backpressure for non-critical metering.
Q. What is a float switch and when is it most useful?A float switch is a very useful device to control the liquid level in a tank. As the liquid level decreases, the float sinks and closes contacts that can be used to control the functions of a pump, such as stopping pump 1 and starting pump 2. It can be used to turn on an alarm or indicator lamp to show that the tank is empty.