The sand blasters

Designations
In the same way the word "sanblasting" is incorrectly used to name surface impact treatment operations, the name "sandblaster" is often used to name the tank under pressure used for the abrasive projection (despite the banning of using sand as an abrasive).
The other common names given to this machine are:
- shot blasters,
- corindum blasters,
- microbeads blasters,
They have the name of the abrasive used. They can also be called projection machine. The equipment of the machine is anyway personalized according to the product projected as well at the hose level (pipe, nozzle carrier and nozzle) as at the level of its abrasive measure, or its closing valve.
It is also used for the dry or wet sandblasting by the attachment of a humidification device at the nozzle level.

Conformity
These machine made according to safety prescriptions and very precise standards are submitted (5 or 10 years) to a check of the "Apave" and a control by the the "French government vehicle testing service" (certificate supplied by the manufacturer).

The different kinds

Design
They are based on the principle of the pressures, equilibrium, as well above as below the abrasive. This allows the hose to be fed by simple gravity making the measuring out more precise.
They are made of:
- a storage tank with a hatch,
- a loading valve and automatic closing,
- an air intake valve for pressurization,
- an air exhaust valve for decompression,
- a valve to measure the abrasive output,
- a set of legs for the fixed sandblasters,
- a train of wheels and a stand for the moving sandblasters.

Capacities
The tank capacity ranges from 20 to 300 liters in common versions and its dimension is calculated to make it possible to have a work autonomy ranging between 30 and 40 minutes.
This choice is made taking into account the abrasive consumption linked to the nozzle diameter and to the use pressure. (see chart air consumptions)
In some cases, the big capacities are used to feed two operators (or more) from a unique machine (see picture below).

Types
There are two kinds of pressure machines: (see evolution)
- the simple body or simple tank machines which require a stop of the projection and a decompression of the body to reload them (see picture above).
- the double body or double tank machines which allow a continuous projection with a reloading without stopping the projection (see picture below).

Utilisations
The first type is used above all on the manual operations in cabins or on sites. The second kind is always used on automatic machines, or on sites when a high output is required.

Controls

Manual control
Two persons are necessary to work the basic sandblaster safely. One operator drives the projection hose to execute the work while another one starts or stops the sandblaster, with a sign of the operator, or at the view of an incident or an accident.
This convention is not always respected on practice for the sake of workforce economy and the danger becomes real and permanent. That is why some engineers settled several systems aiming to suppress the second operator while optimazing safety.

Remote control
The remote control was born and its real function a "dead man safety control". (see opposite picture)
This device is imposed on all sandblasters with a unique operator since 1981, April, 14th through a by-law number 80542-3.

Principle
A control handle is fixed closed to the nozzle.
The pulling down or releasing of this control handle starts or stops the abrasive shot. Therefore, the operator must always support it while working what brings him a 100% safety.
This pneumatic or preferably electric control acts either on two separate valves (pressure and decompression) or on a unique valve with a double function.