Abstract : This paper discusses the advantages of variable frequency speed control water supply equipment in the domestic water supply of multi-story buildings. It discusses variable frequency constant pressure variable flow water supply and variable pressure variable flow water supply, introduces the automatic sleep and automatic wake-up functions of variable frequency pumps in variable frequency constant pressure water supply and their advantages, and reviews the automatic start-up and automatic shutdown methods of multi-pump constant pressure water supply and their advantages and disadvantages.
Keywords : Variable frequency speed control technology, constant pressure water supply
1 Introduction
Early building domestic water supply widely adopted elevated water tank systems, where water was pumped into a high-level tank, and the water flowed to users by gravity. This method had well-known drawbacks, such as the need for elevated water tanks and their susceptibility to secondary contamination. In the 1970s, my country began using pneumatic water supply equipment to replace elevated tank systems. To prevent frequent pump start-stop cycles at low flow rates, the pneumatic tanks required sufficiently large capacities. However, large-capacity pneumatic tanks not only increased costs but also necessitated larger pump rooms. Therefore, the widespread adoption of pneumatic water supply equipment was somewhat limited. The main requirements for building domestic water supply equipment include:
(1) The water supply pressure (H) and flow rate (Q) should meet the usage requirements. For pneumatic water supply and other non-speed-regulating pump water supply methods, the water supply pressure and flow rate are mainly guaranteed by the reasonable selection of pumps. After the pump is selected, the water supply pressure (H) changes with the flow rate (Q) according to the characteristic curve of the pump and cannot be changed. However, there is often a big difference between the actual water flow rate of users and the designed water flow rate. For example, the designed expected water flow rate is different from the actual flow rate. Under different water use conditions, the flow rate is often lower and the water pressure is often higher. In order to prevent overpressure, users often request to reduce the water supply pressure when the whole community is put into use. Under the condition of high flow rate water supply, in order to meet the water pressure of remote users, the water supply pressure is often required to be increased. Since the water supply pressure of pneumatic water supply is not adjustable, while the water supply pressure of variable frequency speed regulation water supply is adjustable, the use of variable frequency speed regulation water supply can well meet the requirements of water supply pressure and flow rate, which can make up for the insufficiency of the design water supply parameters (Q and H) that may not match the actual situation, and can adapt to the requirements of pressure changes under different water use conditions.
For details, please click: Application of Variable Frequency Speed Control Technology in Building Water Supply Equipment
