Chemical laboratory equipment | Common problems and solutions in the application of metering pumps

Author:

　　Metering pump is a machine that can measure the liquid being transported, also called quantitative pump and proportional pump. There are two types of metering pumps: adjustable and non-adjustable. The applicability of adjustable metering pumps is wider. Metering pumps are divided into plunger metering pumps and diaphragm metering pumps. Metering pumps are increasingly used in the chemical, oil refining, pharmaceutical, food and nuclear energy industries. In view of the common problems encountered by some friends in the process of using metering pumps (dosing pumps), here is a summary as follows.

　　One. What are the important things to pay attention to when running the metering pump dosing system?

　　When operating the metering pump dosing system, pay attention to the following matters:

　　A. Put more pressure

　　B. Stroke frequency

　　C. Suction height

　　D. Altitude

　　E. Corrosiveness of chemicals

　　two. When the outlet of the metering pump is at atmospheric pressure, is there any way to improve the repeated metering accuracy of the pump?

　　Installing a valve spring on the discharge valve of a metering pump can improve repeat metering accuracy, but the most effective way to improve is to install a back pressure valve at the end of the pipeline.

　　three. How to adjust the back pressure valve?

　　1. Never exceed the maximum working pressure of the metering pump.

　　2. When the metering pump has pressure on the suction side, the pressure on the discharge side of the pump should be at least 1 bar higher than the pressure on the suction side.

　　four. How to choose the appropriate pulsation damper volume?

　　Multiply the metering capacity (ml) of each stroke of the metering pump by 26 to obtain the minimum volume (ml) of the pulse damper required to reduce 90% of the pulsation.

　　Fives. How to set the pressure of the safety valve?

　　The pressure of the safety valve can be adjusted within the rated working pressure range of the metering pump, and it is not allowed to exceed the maximum working pressure of the metering pump. The safety valve is designed to prevent overpressure operation of the metering pump. For example, if the maximum working pressure of the metering pump is 3bar, the pressure of the safety valve should be set to 3bar or lower to ensure the normal operation of the metering pump. Overpressure work is one of the main causes of damage to the metering pump.

　　six. If the conveyed liquid is not water, how to calculate the suction height?

　　Divide the rated suction height of the metering pump by the specific gravity of the metered liquid.

　　Seven. Under what circumstances should I use self-priming suction?

　　Self-filling suction can be used in the following situations:

　　1. The measured liquid is easy to volatilize;

　　2. The specific gravity of the metered liquid is relatively large;

　　3. When a higher stroke frequency is required;

　　4. When the metering pump is working in high altitude areas;

　　5. In the case where a larger storage tank is required for field application, and it is not feasible to rely on the self-priming of the metering pump.

Shanghai Shunzi Machinery Manufacturing Co., Ltd. (www.shszjx.com) is an enterprise specializing in the development, design, production and sales of various pump products and other mechanical equipment. Our complete process includes focusing on our products used in the entire project. We will provide a variety of comprehensive services, including the preliminary preparations for the project. If there are special requirements, we will do special design and development. The company's products include metering pumps, dosing devices, high-pressure reciprocating pumps, diaphragm pumps, pipeline pumps, screw pumps, magnetic pumps, oil pumps, asphalt pumps, gear pumps, etc. Among them, the industry leader in the research and development and manufacturer of metering pumps, dosing devices, and high-pressure reciprocating pumps.

Key words: