Pinch valves are used to control the flow of fluids. They can be either large or small. The large ones are closed by dual-acting bars that squeeze toward the center of the valve, flattening a flexible sleeve and blocking the flow of fluids. Pinch valves can be manually operated, or actuated by air pressure or push/pull pneumatic cylinders. Smaller versions are typically operated by air pressure.
Internal pinch valves offer a minimized tube length
An internal pinch valve has a reduced tube length. The valve can be configured with an opening Dth that is suitable for the tubing diameter and avoids excessive tubing compression when the valve is fully opened. The valve should also occlude the tube when closed, and completely open. The compression profile of the internal pinch valve can be adjusted, thereby enhancing linearity and flow-rate resolution.
Internal pinch valves are available with varying degrees of wetted materials. Unlike external pinch valves, which feature a single wetted material, internal pinch valves are difficult to adjust. They also require separate qualification for tubing connectors. As such, the internal pinch valve is not suitable for high-volume applications.
The relative error of the valve at 50% of maximum flow rate is the highest for high-pressure applications, even when tubing has low durometer. Pinch valves with high-pressure and low-durometer tubing are less variable. However, the error is still high when a valve is opened.
Airpinch(tm) pinch valves require constant pressure for complete closure
Airpinch(tm) pinch valve housings are precision molded from engineering grade plastics, which makes them lightweight and well suited for applications where metal valves are unsuitable. These pinch valves function by using compressed air or fluid to compress a rubber sleeve, allowing them to achieve a constant closure pressure. The pinch valves operating pressure depends on the type of elastomer used in the sleeve, as well as the size of the valve.
Airpinch(tm) pinch valve housings are designed to withstand pressure fluctuations from a wide range. The airpinch(tm) pinch valves are available with a variety of styles and materials. These valves are generally designed to close completely on large particulate matter and abrasive materials, while allowing full flow without excessive turbulence. Airpinch(tm) pinch valves are reusable and can be replaced when the rubber sleeve becomes worn or damaged.
The required actuation pressure is usually 20 to 40 psi higher than the media pressure. However, the recommended actuation air pressure is still more than enough to achieve complete closure. Using a higher pressure can reduce the sleeve’s life, so it is recommended to use only the recommended actuation pressure.
Lime is a widely used substance in the municipal water and wastewater industry
Lime is an effective treatment for many types of biological waste, including sewage biosolids, industrial sludges, and petroleum wastes. Its many benefits include lowering the pH of wastewater, controlling odors, and immobilizing contaminants. It is also an excellent solution for treating urban biosolids.
Lime is made from limestone, dolomite, and calcium carbonate. It is commonly used to adjust the pH of water that contains acids. It is processed in different ways to make different products. In the manufacturing process, quicklime is created by heating calcium carbonate and releasing carbon dioxide, while hydrated lime is produced by crushing limestone.
Lime is also used as a neutralizer for coagulants, which helps with the separation of dissolved metals. It neutralizes negative charges in suspended particles and helps coagulate larger particles, called flocs, into smaller particles called “flocs”. These particles are then removed from water by sedimentation and filtration.