Acme automatic scraper strainers, self cleaning strainers, pipeline strainers

The Acme ACRS Automatic Scraper Strainer is a motorized unit designed for the continuous removal of suspended solids from intake, process and wastewater flows.

These units can handle heavy solids loading with particles as small as 75 microns and as large as 150mm (6" stones). Our strainers have been installed on applications where backwash strainers have suffered premature clogging, such as black liquor, heavy oils, wax, unprotected river water intakes and boiler waste slurries.

Cleaning is accomplished by a spring-loaded blade and brush system managed by a fully automatic control system. The blades remove larger solids while the brush clean out the individual slots of the wedgewire filtration element, removing smaller particles. The spring-loaded mechanism maintains blade and brush contact with the screen at all times. A separate blowdown timer allows the accumulated solids to be expelled from the bottom of the strainer vessel where they are collected during the scraping cycle. Having a separate blowdown cycle allows our scraper strainer to use far less fluid for cleaning than competing backwash designs.

The ACRS Scraper strainers are available in sizes 2" through 36" in fabricated construction using carbon steel, stainless steel and assorted alloys. All strainer vessels are designed and built in general accordance with ANSI and ASME Sec. VIII, Div. 1. Nozzle arrangements can be offset (standard), in-line at the top and at the bottom of the vessel.

ACME ACRS Automatic Scraper Strainers are used in nearly every industry to strain river, lake or seawater intakes for plant cooling water, fire protection and process requirements.

Process Industry - Protect heat exchangers, pumps, valves and water spray nozzles.

Power Industry - Protect heat exchangers, pump seal water, boiler wash water nozzles.

Wastewater Treatment - Straining secondary effluent to protect spray nozzles and provide plant service water.

Metal and Mining Industries - Provide clean water for quenching, de-scaling, blast furnace cooling.

The fluid enters the strainer vessel and passes down into the wedgewire screen filtration chamber, where the inside to outside flow traps the debris on the inside of the screen. The flow is uninterrupted and the strained clean fluid continues into the outer ring of the strainer body and exits through the outlet nozzle.

The scraper blades and brushes make direct contact with the screen, ensuring that all particles are removed from its surface, including sticky contaminants like sludge, residue, etc. The blades also act as a pulverising agent, capable of breaking up large solids so that they can be more easily evacuated through the blowdown line. Backwash strainers cannot pulverise large contaminants, which increases the risk of their being stuck in the backwash arm during removal, or they remain inside the strainer body pending manual removal. The blowdown line on the scraper strainer is an opening at the bottom of the unit, where contaminants collect during the scraping cycle. Contaminants do not have to traverse a complicated pathway like a backwash arm during their removal.

The control panel includes two timers, one to control the interval between scraping cycles and another to control the length of time that the blowdown valve shall remain open at the end of a scraping cycle. For example, if a scraping cycle lasts two minutes, particles can accumulate at the bottom of the unit pending the opening of the blowdown valve. The blowdown valve would be programmed to open for ten seconds at the end of each minute of the scraping cycle, making for two blowdowns per cycle. With this logic of operation, the scraper strainer uses much less fluid for self-cleaning than backwash strainers, which must open their backwash valves continuously during the cleaning cycle. Also note that our unit uses only unstrained water for blowdown, not clean water sucked back across the screen. Fluid loss can be adjusted for minimum loss requirements. Blowdown operation is controlled by a pneumatically or electrically actuated ball valve on most units and a knife gate valve for more demanding applications.

The control panel also incorporates a DPS (Differential Pressure Switch), which will over-ride the scraper and blowdown timers if the high differential pressure set point is reached. The DPS will operate the scraper mechanism and open the blowdown valve simultaneously until the HPD condition has been cleared. Control panels are available in a wide range of designs and voltages and can also incorporate controls for other related process equipment if required.