Scraper Assembly for Rotary Drum Vacuum Filters

Product Specifications

Technical details and manufacturing context for Scraper Assembly

Definition

The scraper assembly is a critical component of an industrial rotary drum vacuum filter, responsible for the continuous and efficient removal of the filter cake (accumulated solids) from the rotating drum's filter media surface. It ensures the filtration process remains uninterrupted by preventing cake buildup that would otherwise reduce filtration efficiency and capacity. The assembly is typically mounted at a specific angle and position relative to the drum, using a rigid blade or knife-edge to shear the formed filter cake from the drum's surface as it rotates. The contact pressure and angle are precisely controlled to ensure complete cake removal without damaging the underlying filter cloth or media. Materials commonly used include stainless steel (e.g., 304, 316), abrasion-resistant alloy steel, and polyurethane or rubber for blade tips. Key parameters include blade width (500–3000 mm), thickness (3–10 mm), material (SS304/316L, PTFE, UHMWPE per ASTM A240), edge angle (15–45°), clearance (0.5–3.0 mm), operating pressure (0.2–0.6 MPa), temperature (-10–80°C), linear speed (0.1–0.5 m/s), positioning accuracy (±0.05 mm), weight (20–150 kg), mounting hole diameter (10–20 mm per ISO 273), and surface roughness (Ra 0.8–3.2 µm per ISO 4287). These values are reference ranges and must be verified for the specific model and application. The scraper assembly is selected based on drum dimensions, cake characteristics, and process conditions. It interfaces with the filter frame and drive system, and its performance is verified through cake removal efficiency and media wear. Maintenance signals include uneven cake removal, increased wear on the blade, or changes in clearance. Failure boundaries include blade breakage, excessive wear, or loss of contact pressure, which can lead to reduced filtration performance. Always confirm model-specific values and standards with the legal manufacturer or supplier.

Working Principle

The scraper assembly operates by positioning a rigid blade against the rotating drum surface. As the drum rotates, the blade shears the filter cake from the media. The blade angle and contact pressure are adjustable to match cake properties. The blade is typically mounted on a support frame with pneumatic loading to maintain consistent pressure. The clearance between blade and drum is set to avoid damage while ensuring complete removal. The blade's linear speed corresponds to drum rotation speed, and the assembly is designed to handle various cake thicknesses and materials.

Common Materials

Stainless Steel (e.g., 304, 316), Abrasion-Resistant Alloy Steel, Polyurethane or Rubber (for blade tips)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Blade Width	500–3000 mm	Match drum face width
Blade Thickness	3–10 mm	Thicker for abrasive solids
Blade Material	SS304/316L, PTFE, UHMWPE	Corrosion and wear resistanceASTM A240
Blade Edge Angle	15–45 °	Lower angle for softer cakes
Blade-to-Drum Clearance	0.5–3.0 mm	Adjustable; too small causes wear
Operating Pressure	0.2–0.6 MPa	Pneumatic loading force
Operating Temperature	-10–80 °C	Higher for special materials
Blade Linear Speed	0.1–0.5 m/s	Match drum rotation speed
Positioning Accuracy	±0.05 mm	Ensures uniform cake removal
Weight	20–150 kg	Depends on width and material
Mounting Hole Diameter	10–20 mm	For bolting to support frameISO 273
Surface Roughness	Ra 0.8–3.2 µm	Smoother for sticky materialsISO 4287

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Scraper Blade / Knife Part
Primary contact element that physically separates the filter cake from the drum surface.

Material: Abrasion-resistant steel or polyurethane-coated steel
Blade Holder / Mounting Bracket Part
Secures the scraper blade and allows for precise adjustment of its angle and position.

Material: Carbon steel or stainless steel
Adjustment Mechanism
Allows for fine-tuning of the blade's contact pressure, angle, and alignment during operation and maintenance.

Material: Steel
Support Frame Part
Provides rigid structural support for the entire assembly, attaching it to the main filter frame.

Material: Carbon steel
Pneumatic Loading Unit
Presses the blade against the drum with constant force as the blade and drum wear.

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Frequently Asked Questions

What is the function of a scraper assembly in a rotary drum vacuum filter?

It continuously removes the filter cake from the drum's surface to maintain filtration efficiency and prevent clogging.

What materials are commonly used for scraper blades?

Stainless steel (304, 316), abrasion-resistant alloy steel, and polyurethane or rubber for blade tips, depending on the application.

How is the blade-to-drum clearance adjusted?

The clearance is adjustable, typically between 0.5 and 3.0 mm, and must be set to avoid wear while ensuring complete cake removal.

What standards apply to scraper assembly parameters?

Relevant standards include ASTM A240 for blade material, ISO 273 for mounting holes, and ISO 4287 for surface roughness. Verify compliance with the manufacturer.

Data Basis

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Preliminary Technical Classification

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pressure:	Atmospheric to 0.5 bar (7.25 psi) vacuum
flow rate:	Dependent on drum speed and scraper geometry
temperature:	Ambient to 100°C (212°F)
slurry concentration:	5-40% solids by weight

Scraper Assembly

Product Specifications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

Reliability & Engineering Risk Analysis

Compliance & Manufacturing Standards