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5.12 Blast Hose

The blast air, water and abrasive mixture flows from the Thompson® Valve (#14) to the blast
nozzle  (#11)  through  the  blast  hose  assembly  (#10).  The  typical  length  of  the  blast  hose  is
100ft;  however  blast  hose  extensions  can  be  added  to  increase  length.  For  higher  efficiency
keep the blast hose as short as possible. Increased blast hose length causes pressure drop at the
blast nozzle which reduces the blast  efficiency. For higher efficiency use a blast hose with an
inside diameter that is approximately three times the nozzle throat diameter. Keep the blast hose
as straight as possible. Sharp bends create high wear points. Static electricity is generated by the
abrasive  flow  through  the  blast  hose.  To  minimize  the  chance  of  static  electrical  shock  to
operating  personnel  only  use  static  dissipating  blast  hose  and  install  a  grounding  strap  on  the
abrasive blaster.

Static electric shock hazard. To minimize the chance of static electric shock install a grounding
strap on the abrasive blaster and only use static dissipating blast hose.

CRITICAL:

To function properly, a full port threaded coupling (#27) is required on the outlet

of the injection module (#32). If the blast hose assembly (#10) being used does not have a full
port hose coupling (#26), install the provided 1-1/2” x 3’ lg. adapter hose (#73) between the full
port threaded coupling (#27) and the blast hose assembly (#10).

Note:

To reduce operator fatigue a blast whip hose can be used along with the blast hose. A

whip hose is thinner wall and lighter weight hose. Consult an Authorized Schmidt® distributor.

5.13 Blast Nozzle

The blast nozzle (#11) is an important part of the blast operation since the size of it determines
the air flow and abrasive requirement. The amount of air flow and abrasive determine how

quick blasting can be done. The larger the nozzle, the more air and abrasive will be needed. The
larger the nozzle size the greater the blast productivity. However, for a fixed amount of air
supply, increasing the nozzle size will reduce the blast pressure. For best performance the blast
pressure must be maintained as high as possible. Therefore, select the nozzle size based on the
amount of air available and then adjust the abrasive flow at the Thompson® Valve (#14) as
needed.

The nozzle size is indicated by a small number on the outside. This number represents the
nozzle throat diameter in sixteenths of an inch; for example, a #5 nozzle has a throat diameter
of 5/16". See the tables in Section 13.0 for approximate air and abrasive consumption for each
nozzle.

Note:

For the best possible mixture of air to abrasive, the blast hose and piping must be

at least three times the size of the blast nozzle.

5.14 Hose Connection

All air hose, blast hose, and threaded couplings have two pin holes that align when connected.
To  protect  against  accidental  hose  disconnections,  safety  pins  must  be  installed  through  these
holes.  As  a  secondary  safety  measure  each  hose  connection  should  also  include  a  hose  whip
check that will hold the hose if there is an accidental disconnection. Connect one loop to each
side  of  the  connection  and  stretch  out  as  shown  in  Figure  5.4  below.  All  air  hose,  blast  hose,
and threaded couplings have a gasket that seals the connection and should be replaced when air
is leaking.

Failure to install safety pins on all air and blast hose couplings can result in hose disconnects
and could result in serious injury or death.