Walk-In Acid Digestion Hood

What is the Walk-In Acid Digestion Hood?

A walk-in acid digestion hood has a floor-level work area that allows operators to load large racks and tall vessels. It is used for high-throughput multi-vessel acid digestions in mining, metallurgical and environmental laboratories.

Overview

The hood extends to the floor, so large digestion racks, carboys and tall glassware can be wheeled in without lifting. Construction is welded polypropylene with a stainless or ceramic floor and a full-height sash or door system. Height is 2000–2500 mm, depth 900–1500 mm and width 1500–2400 mm, giving multi-level racks room to operate. Airflow is higher than a benchtop hood, typically 1000–2500 m3/h, to hold 0.4–0.6 m/s across the larger opening. Multiple baffle positions and a washdown system handle the larger vapour load. A scrubber is often integrated. Internal lighting, power outlets and a drainage sump are provided, and the design is commonly paired with a winch or trolley for heavy racks.

How does it work?

An acid digestion hood encloses the hotplate or block digester on a chemically resistant work surface and draws acid vapours away through a rear baffle and exhaust duct. The body, liner and sash are made from polypropylene, PVC or acid-resistant stainless steel so that nitric, hydrochloric and hydrofluoric acid vapours do not corrode the surfaces. Face velocity at the sash is held at 0.4–0.6 m/s, and a corrosion-resistant fan, usually plastic or PVC-coated, moves air to atmosphere. Because digestion releases dense acid fumes and heat, larger air volumes and deeper baffles are used than in a general-purpose hood. Some models add a scrubber that neutralises acid in a packed column before discharge, reducing emissions to the stack. Water washdown and low dead volume help prevent salt accumulation and cross contamination between trace-metal samples.

What are the key features?

• Floor-level work area for large racks
• Welded polypropylene, 10–15 mm panels
• Height 2000–2500 mm, width 1500–2400 mm
• Airflow 1000–2500 m3/h at 0.4–0.6 m/s
• Full-height sash or door with safety interlock
• Integrated washdown and drainage sump

What are the technical specifications?

A typical walk-in acid digestion hood configuration offers body material of Welded polypropylene, 10–15 mm, height of 2000–2500 mm, width of 1500–2400 mm, depth of 900–1500 mm, face velocity of 0.4–0.6 m/s and airflow of 1000–2500 m3/h. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Walk-In Acid Digestion Hood is used in multi-vessel high-throughput digestion, mining and metallurgical assay, environmental batch analysis and large-sample composite digestion. Across the wider Acid Digestion Hoods class, laboratories also deploy it for trace-metal sample digestion, environmental soil and water analysis and food and feed elemental analysis.

Which standards and certifications apply?

Relevant standards and methods include EN 14175-2 (fume cupboards, safety and performance), EN 14175-3 (type test methods), ASHRAE 110 (method of testing performance of laboratory fume hoods), GB/T 34269, ASTM D1193 (reagent water used in digestion blanks) and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Install the hood away from doors and air supply diffusers, and provide corrosion-resistant ducting with the correct slope and drainage. Commission face velocity and, where required, containment by tracer gas at the sash. Establish a hotplate and acid-usage log, and inspect the liner, sash and fittings monthly for etching or discoloration. Replace exhausted scrubber media on the schedule set by the acid load, and treat scrubber effluent as acidic waste. Keep the work surface clean and free of salt deposits, especially around the inside of the duct connection. Provide secondary containment trays and confirm the fan, duct and roof discharge are rated for the acids in use.

How do I select the right Walk-In Acid Digestion Hood?

Choose a walk-in hood for multi-level racks, tall glassware or heavy carboys that cannot be lifted onto a bench. Confirm floor load, trolley access and door clearance. RFQ: rack dimensions, vessel count, acids and volumes, drain requirements and any scrubber requirement.

How does it compare with other Acid Digestion Hoods variants?

Choose the construction from the acids used. Hydrofluoric acid attacks glass and requires polypropylene or special liners; nitric and hydrochloric acid work needs polypropylene, PVC or acid-grade stainless steel. Decide whether a scrubber is required by local emission limits and the acid volumes handled. Match the internal height to the hotplate, rack and reflux glassware, and choose depth for tall condensers. Consider a dedicated water washdown system if the duct could collect salts. Select face velocity monitoring and alarms, and a work surface with a spill lip. Confirm the fan is corrosion-resistant rather than mild steel, and plan for acid-resistant duct material and drainage. Large multi-position digestions may need a walk-in or dual-duct layout.