博文

What Is the Function of the Recirculation Hole in a Self-Priming Pump?

 What Is the Function of the Recirculation Hole in a Self-Priming Pump? In the structural design of a self-priming pump, there is a small but very important component called the recirculation hole (or return hole). Although it looks simple, it plays a key role in ensuring that the pump can successfully complete the self-priming process. When a self-priming pump starts, there is usually air inside the suction pipe and the pump chamber. The pump must remove this air before it can begin normal liquid delivery. At this stage, the recirculation hole helps create a continuous liquid circulation inside the pump, which assists in separating and discharging the air. During operation, the impeller rotates at high speed, throwing the mixture of liquid and air toward the outer part of the pump casing. The air is separated and discharged, while the liquid returns to the impeller inlet through the recirculation hole. This process forms a repeated gas-liquid circulation loop. After several cycles...
发表评论
阅读全文

Problems Diaphragm Pumps Face in Low-Temperature Conditions

 Problems Diaphragm Pumps Face in Low-Temperature Conditions In cold climates and winter operating environments—such as chemical plants, wastewater systems, cold-chain facilities, and outdoor pumping stations—diaphragm pumps are widely used for their self-priming capability, excellent sealing, and corrosion resistance. However, many users notice that diaphragm pumps tend to fail more often or perform poorly in low temperatures. Understanding why these failures occur can help engineers prevent costly downtime. If you’d like to dive deeper into a detailed analysis, check this link from Shanghai Shangcheng Pump Valve (SCPV): 🔗 https://www.scpv.cn/news/249.html 1. Diaphragm Hardening and Cracking The diaphragm is the heart of a diaphragm pump—commonly made from elastomeric or composite materials. In low-temperature environments: Elastomer materials stiffen Elasticity decreases Fatigue resistance drops This leads to: ✔ Reduced flexing performance ✔ Higher stress concentration ✔ Cracks ...
发表评论
阅读全文

Can Screw Pumps Run Dry? Structural Differences Explained

 Can Screw Pumps Run Dry? Structural Differences Explained In many industrial sites, operators sometimes assume that “a few minutes of dry running won’t hurt.” But when it comes to screw pumps, the reality is very different. Whether a screw pump can tolerate dry running depends entirely on its internal structure. Making the wrong assumption can result in rapid wear, seal failure, or even complete pump damage. What Is Dry Running? Dry running occurs when a pump operates without sufficient liquid inside the casing for lubrication and cooling. Common causes include: Starting without priming Low tank level Blocked suction line Intermittent material supply For positive displacement pumps like screw pumps, this is a high-risk condition. 1️⃣ Single Screw Pump (Progressive Cavity Pump) Structure: Metal rotor Elastomer stator Sealed cavities formed between rotor and stator This design relies heavily on the pumped fluid for lubrication and cooling. If dry running occurs: Friction temperature...
发表评论
阅读全文

How the Balance Disc Protects a Multistage Pump

 How the Balance Disc Protects a Multistage Pump When people talk about multistage centrifugal pumps, they usually focus on head, efficiency, or mechanical seals. But in high-head applications, one critical component determines long-term reliability: the balance disc. In every multistage pump, each impeller generates axial thrust. As the number of stages increases, the axial force accumulates. Without an effective balancing device, this force can: Overload the thrust bearing Cause shaft axial movement Damage mechanical seals Increase vibration and shorten service life That’s why a properly designed balance system is essential. What Does a Balance Disc Do? The balance disc is a hydraulic axial force compensation device. Its job is simple in theory but sophisticated in operation: It uses pressure differential to generate a counteracting force. High-pressure liquid from the pump discharge enters the balance chamber. A small clearance between the balance disc and balance ring allows co...
发表评论
阅读全文

Operating a Centrifugal Pump at Minimum Flow — Hidden Risks Many Plants Overlook

 Operating a Centrifugal Pump at Minimum Flow — Hidden Risks Many Plants Overlook Centrifugal pumps are widely used in water supply, chemical processing, cooling circulation, and industrial fluid transfer systems. However, in many facilities, pumps are operated for long periods under minimum or low-flow conditions simply by throttling the discharge valve. Although the pump may appear to run normally, this operating method can gradually damage internal components and significantly reduce service life. In practical engineering applications, manufacturers such as Shanghai Shangcheng Pump & Valve often find that premature pump failures are caused not by product quality, but by long-term operation away from the designed flow range. 👉 Learn more about centrifugal pump solutions: https://www.scpv.cn/lixinbeng/ 1. Excess Heat Build-Up Inside the Pump A centrifugal pump relies on flowing liquid to remove heat generated during operation. When operating below minimum flow: Liquid continu...
发表评论
阅读全文

Hidden Risks of Wrong Chemical Pump Material Selection — A Long-Term Cost Many Plants Ignore

 Hidden Risks of Wrong Chemical Pump Material Selection — A Long-Term Cost Many Plants Ignore In chemical processing systems, pump performance is not determined only by flow rate or pressure. In reality, material selection is the most critical factor affecting long-term reliability. Many industrial failures are not caused by poor manufacturing quality, but by incorrect material matching during the early selection stage. Manufacturers such as Shanghai Shangcheng Pump & Valve emphasize evaluating fluid characteristics before choosing pump models, because improper materials can create long-term operational risks. 👉 Chemical Pump Solutions: https://www.scpv.cn/huagongbeng/ 1. Corrosion Problems Often Appear Later A chemical pump may operate normally during initial installation. However, after several months of operation, hidden corrosion begins to appear. Common consequences include: Pump casing corrosion Impeller thinning Reduced hydraulic efficiency Chemical media such as acids,...
发表评论
阅读全文

How Stroke Length Adjustment Controls Metering Pump Accuracy

 How Stroke Length Adjustment Controls Metering Pump Accuracy In chemical dosing, water treatment, and industrial injection systems, a metering pump is valued for one key capability — precise flow control. Many users assume flow adjustment depends on motor speed. In reality, most metering pumps regulate flow by changing the stroke length. What Is Stroke Length in a Metering Pump? Stroke length refers to the moving distance of the diaphragm or plunger during one reciprocating cycle. The principle is straightforward: Longer stroke → larger discharge volume per cycle Shorter stroke → smaller discharge volume Constant speed → stable dosing frequency So the output flow rate is mainly controlled by adjusting how much liquid is displaced in each stroke. Mechanical Principle Behind Stroke Adjustment Inside a metering pump, rotational motion from the motor is converted into reciprocating motion through: Eccentric cam mechanism Connecting rod system Diaphragm or plunger assembly When the adj...
发表评论
阅读全文