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Posted: Apr 27, 2017 Clicks: 917

B4C Sandblast Nozzles

Sand blasting refers to the cleaning of surfaces by the action of an abrasive flow, which is sent by compressed air with high acceleration to the object to be cleaned through the nozzle. It would be more correct to call this process abrasive blasting, because The most commonly used abrasive materials are steel and cast iron shot, cupper slag, electrocorundum and sand, however, in the future we will use the generally accepted name "sand blasting" in practice. 

Using the sandblasting method, the following "surface preparation" is performed: 

- removal from the surface of rolling scale, rust, residue, residual molding 
Mixture, for (newly manufactured products) 
- removal of old coatings for (recoverable products) 
- creating a microrelief - giving a surface roughness (on a smooth surface) 
- surface hardening, removing surface stresses and increasing resistance to cyclic loads (springs, springs, etc.) 

Along with the cleaning of metal surfaces, the sandblasting process is also used for the matting of glass for decorative purposes, when removing remnants of varnishes and paints from wood, when cleaning objects from plastic (eg dentures, electronic parts, etc.). It is also used for the removal of layers on concrete, for cleaning facades of buildings, in the leather industry and in many other industries. 

All sandblasting works are carried out in compliance with the requirements of GOST 9.402-2004 "Coatings for paint and varnish. Preparation of metal surfaces before painting or ISO 8501-1988 "Preparation of steel substrates before application of paints and similar coatings" 

General description of sandblasting process 

Basically, there are two ways to apply the abrasive to the nozzle: 

Supply under vacuum - injection plants. 

Injection plants are used to clean small items in a relatively small amount. This is determined by the small capacity of these units, about 3 to 5 m2 / h. Most often this method of cleaning is used in small chambers, where the processing zone is only the hands of the operator. 
Feeding under pressure - installation of pressure type. 

The pressure-type sandblasting machine (installation) is widely used for cleaning large areas or difficult-to-work elements of a structure, for example: shipbuilding, railway, cleaning of buildings, bridges, steel or other large area structures. This is determined by the high productivity of these units, about 15-25 m2 / h. 

The maximum efficiency of pressure type installations can be achieved only if all components important for the sandblasting process are selected correctly: 

- With sufficient feed power and sufficient pressure. 
- The quality of the supplied air (moisture and oil content) complies with the requirements of GOST 17433-80 or ISO 8573.1 

Hose sizes 
- The internal diameter of the hose for air supply from the compressor to the sandblaster is matched with minimal loss of air parameters. 
- The internal diameter of the jet hose is 3-4 times larger than the nozzle opening. 

Hose connections 
- Hose connections have the same internal diameter as the entire hose. 

Sandblasting Nozzle 

1. The diameter of the nozzle should be not less than 4 times the diameter of the abrasive used 

2. The diameter of the nozzle also affects the nozzle power 
Taking as 100% the power of the nozzle with a 1/4 "= 6 mm hole, we get the following picture: 

The nozzle with an aperture of 5/16 "= 8 mm has a power of 157% 
The nozzle with a 3/8 "hole = 9.5 mm has a power of 220% 
The nozzle with a hole of 7/16 "= 11 mm has a power of 320% 
The nozzle with a 1/2 "hole = 12.5 mm has a power of 400% 

3. The length of the nozzle also affects the power of the nozzle, with the nozzle's unchanged diameter 
The following picture: 

Nozzle The straight 11mm length 75mm has a power of 100% 
Nozzle The straight 11mm length 150mm has a power of 115% 

4. The nozzle type also affects the nozzle power with the same diameter 
Nozzle Direct has a power of 100% 
The Venturi nozzle has a capacity of 125% 
The nozzle with a double Venturi has a power of 140% 

5. The influence of the jet pressure on the jet power with the nozzle diameter unchanged has 
The following picture: 

The nozzle that emits a jet at 7 atm -100% of the surface 
Nozzle that emits a jet at 5.6 atm - 66% of the surface 
Nozzle, jetting at 4.2 atm - 50% of the surface 

Sandblasting equipment of pressure type 

1. The design of the apparatus tank shall comply with the international safety requirements for pressure receptacles. The certificate of verification of the tank should be supplied by the manufacturer with the tank. 

2. The apparatus should have a simple construction of pipelines and, if possible, fewer fittings and bends. In order to achieve high power, the minimum pipe bore must be 1 "or 11/4" = 32 mm. 

3. The machine should work equally well with all types of abrasive. 

4. The device must be equipped with self-closing rubber