Scientific blog · Technology and flue gas treatment
Smoke and grease scrubber for charcoal grills and steak houses: NEWSCRUB AH — ROASTER
Artur Cokaj ·
Five water-based scrubbers for charcoal grills, steak houses and rotisseries, from 2,500 to 14,000 m³/h: model data, standard equipment, IMQ certificate 297 and test reports.
For charcoal grills ETC Group builds a dedicated family of water-based scrubbers, the NEWSCRUB AH — ROASTER: five models, from the NEWSCRUB AH 300 PLUS — ROASTER (up to 2,500 m³/h) to the NEWSCRUB AH 600 — ROASTER (up to 14,000 m³/h). Flue gas from embers carries soot, ash and grease atomised from the meat, which together form deposits much harder than those of a wood-fired oven. For this reason grill machines have more powerful pumps, larger tanks and a motorised drain as standard.
AH 350, AH 400, AH 500 and AH 600 are covered by type-examination certificate no. IMQ 297 Rev. 0 of 16/07/2018 (file 50AR00040), issued to ETC Group by IMQ, a notified body, on the essential requirements of Machinery Directive 2006/42/EC. Dust reduction of 95.2% measured by ACCREDIA LAB no. 0656, reports 14LA11644 and 14LA11645.
Why does a grill not use the same scrubber as a wood-fired oven?
Grease dripping onto the embers evaporates and condenses in the ducts and in the washing water. With a scrubber designed for ovens the water loads up quickly, foam forms and the deposits in the tank harden. ETC specifies the ROASTER family whenever there is a grill under the hood, even if the fuel is the same as for an oven.
The five ROASTER models
| Model | Airflow with extractor fan | Flue connection | W × D × H | Water in tank | Pump | Power supply |
|---|---|---|---|---|---|---|
| NEWSCRUB AH 300 PLUS — ROASTER | up to 2,500 m³/h | Ø 300 mm | 1,050 × 750 × 960 mm | 140 l | 1.3 kW | 230 V single-phase |
| NEWSCRUB AH 350 — ROASTER | up to 4,500 m³/h | Ø 350 mm | 1,225 × 800 × 1,170 mm | 210 l | 1.5 kW | 230 V single-phase |
| NEWSCRUB AH 400 — ROASTER | up to 5,000 m³/h | Ø 400 mm | 1,350 × 1,140 × 1,060 mm | 270 l | 1.85 kW | 230 V single-phase |
| NEWSCRUB AH 500 — ROASTER | up to 10,000 m³/h | Ø 404 mm | 1,580 × 1,680 × 1,500 mm | 500 l | 3 kW | 230 V single-phase |
| NEWSCRUB AH 600 — ROASTER | up to 14,000 m³/h | Ø 640 mm | 1,580 × 1,680 × 1,300 mm | 500 l | 2.2 kW | 380 V three-phase |
The airflows are those achievable with a matched extractor fan. Without forced extraction the airflow is much lower: on the NEWSCRUB AH 400 — ROASTER it is 1,300 m³/h.
What is standard on all ROASTER models
AISI 304 stainless steel structure, 1.5 mm (15/10) thick, with base frame, motorised ball drain valve with an all-stainless-steel body and 30 Nm actuator, partial front stainless steel cover for outdoor use.
On request ETC supplies the full cover (aluminium profiles with double sandwich panelling), the support for mounting the extractor fan on top of the machine with anti-vibration mounts, and the extractor fan with inverter. For grills with a very high grease load ETC can provide from the outset a double valve with additional water supply, which uses the overflow to remove floating grease.
How is the model chosen?
The hood airflow determines the model. For an island hood ETC calculates the airflow as hood perimeter times height between hood and cooking surface times a capture velocity of 0.5 m/s; in the duct the velocity stays within 15 m/s. For 1,500 m³/h the smallest suitable model is the NEWSCRUB AH 300 PLUS — ROASTER. The extractor fan is selected on its curve, at the operating point, and must be installed after the scrubber: if it is placed before, it pressurises the machine and smoke escapes from hatches and joints.
What remains after washing?
Soot and the larger particles remain in the water. Visible smoke and meat odours decrease but do not disappear. After a water-based scrubber the air is saturated with moisture: electrostatic filters downstream are not a solution and ETC does not offer them. The only treatment ETC adds is an ozone generator, which works on odours.
Maintenance on a grill
Drains and water changes are more frequent than on an oven and the motorised valve performs them on a timer. If foam forms, drain, rinse and restart with clean water; if it returns immediately, increase the frequency of water changes. The duct between hood and scrubber is cleaned at least every three months. Detergents and deodorants must not be used in the tank unless instructed by the ETC technical department.