TAILIEUCHUNG - A Practical Guide to Particle Counting for Drinking Water Treatment - Chapter 22

Grab lấy mẫu Tất cả bốn người trong số các nhà sản xuất cung cấp lấy mẫu lấy, Met, Chemtrac, và ARTI dẫn đầu. IBR vẫn cung cấp các đơn vị Royco Hiac ban đầu được thiết kế cho Hach như của các đơn vị tương tự như kích thước và trọng lượng, và hoạt động giống như cách "Đăng nhập dễ dàng". | CHAPTER 22 Grab Samplers All four of the manufacturers offer grab samplers with Met One Chemtrac and ARTI leading the way. IBR still offers the Hiac Royco unit originally designed for Hach as the Log Easy. Each of the units is similar in size and weight and operates in like manner. A. EQUIPMENT FEATURES The ARTI WQA 2000 Met One WGS-267 Grab Sampler and the Chemtrac 2400 PS are designed to operate in grab or continuous online mode. The IBR can as well although its internal pump cannot be bypassed. The pumps in each of these units are not designed for continual operation so it is recommended that long-term online applications be set up using a constant-head overflow weir and gravity flow. 1. Sample Delivery System All of the units employ small DC gear pumps that pull the sample through the sensor. The speed of the pump is controlled by a DC voltage source which is not user adjustable. The ARTI WQA 2000 and the Met One WGS-267 employ a user-adjustable needle valve rotometer to allow the operator to adjust the flow rate. The other units provide no flow adjustment or display. The gear pumps provide a smooth quiet pulseless flow and can clog if large concentrations of particles are present. They are designed for around 400 hours of operating life which will cover several years worth of grab sampling but only a few weeks of continuous operation. The ARTI Chemtrac and Met One units are easily converted to continuous online operation by moving a couple of pieces of tubing. This allows for the pump to be bypassed and connection made to a gravity flow system. 195 2001 by CRC Press LLC 196 A PRACTICAL GUIDE TO PARTICLE COUNTING All of the units operate off AC power and rechargeable DC batteries. Battery operation provides ease of portability as well as reducing the electrical shock hazard when operated in a wet environment. 2. Packaging The Chemtrac 2400 PS is packaged in a standard NEMA 4X plastic box with the sensor extending from the side. This allows the sample flow to be

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