What is the ZDT series automatic recirculation pump protection valve

The ZDT series automatic circulation pump protection valve (three-way reflux valve) is a pump protection device. It automatically protects the centrifugal pump (especially for transporting hot water medium) from potential cavitation damage and instability that may occur inside the pump body during low load operation. Once the pump flow rate falls below the preset flow rate, the bypass opens to ensure the minimum flow rate required by the pump. Even if the main channel is closed, i.e. the main channel flow is zero, the minimum flow can still be automatically circulated through the bypass. The pressure is reduced through an integrated multi-stage throttling pressure reducing valve in the bypass. The ZDT series has a larger caliber bypass. This valve is used for larger bypass flow rates, with a maximum pressure difference of up to 4MPa, and the specific selection is determined by the factory.

What are the characteristics of the ZDT series automatic recirculation pump protection valve?

Simple structure, reliable and stable operation, with only a few moving parts.

Easy to install, can be installed vertically or horizontally at the pressure outlet of the pump.

The bypass flow is large, up to 60% of the main flow, and the KV value can be adjusted.

The maximum working pressure difference of the bypass is 4MPa. You can choose to add a bypass check function.

Suitable for other liquid media such as water, oil, methanol, etc. The working temperature ranges from -196 ℃ to+300 ℃.

The working principle of the ZDT series automatic recirculation pump protection valve

According to the different detected main flow rates, the check cone of the main valve disc of the automatic recirculation valve will automatically move to a certain position. At the same time, the main valve disc drives the bypass valve stem, transmitting the action of the main valve disc to the bypass. By controlling the position of the bypass valve disc, the throttling area of the bypass is changed, thereby controlling the flow through the bypass. When the main valve disc returns to the closed state of the valve seat, all flow returns through the bypass. When the main valve disc rises to the top position, the bypass is closed and the flow of all pumps flows to the process system. This valve integrates four functions into one.

Flow sensing: The main valve disc of the automatic recirculation valve can automatically sense the main flow in the process system, and determine the position of the main valve disc and bypass valve disc based on this flow.

Recirculation control: the automatic recirculation valve can suck the minimum flow required for the normal operation of the pump into the storage device through the bypass, regulate the H-Q characteristics of the pump, and achieve recirculation.

Bypass multi-stage pressure reduction: The bypass control system can reduce the high pressure of the reflux medium from the pump outlet to a suitable low pressure in the reflux storage device with low noise and minimal wear.

Check valve: The automatic recirculation valve also serves as a check valve to prevent liquid from flowing back into the pump body. ZDT bypass check is an optional function.

Other bypass sizes can be made according to requirements; The maximum bypass flow depends on the maximum Kv value