DUSTLESS BLASTING DB150 User manual

DB500®User Manual
Warning: Do not use this equipment until you have read the manual
and understand the contents. *User safety is always a
top priority. However, the safety of an intended user
can only be protected if outlined precautions are read
and followed carefully. *International Distributors are
responsible for the proper translation of this manual.

2
TABLE OF CONTENTS
I. Introduction………………………………………………………………………………………..….4
Notice Symbols……………………………………………………………………………………..4
Blast Pot Warranty……...…..……………………………………………………………………..5
Safety Overview………………..…………………………………………………………………..6
II. Abrasives……………………………..………………………..……………..…………….…………7
Selecting an Abrasive……………………….………………………………………….………….7
Abrasive shape……………………………………………………………………………..7
Abrasive size, density, and hardness……………..……………………………………….7,8
Media Comparison Charts………………….……………………………………….……….…...8
Figure 3. Dry Blasting Abrasive………………………………………………..…….……..8
Figure 4. Wet or Dry Blasting Abrasive…….……………………………………………….9
Abrasive Fill Levels……………………………………....………..…………………….……….10
III. Preparing to Blast………………………………..…………………………………….…..……11
Personal Protective Equipment………………………...……………………………………….11
Masking and Containment...…..………………………………………………………..……….11
Model DB500®……...…………..………………………………………………………..……….12
IV. Blast Pot Start Up………………...…...………………………………………………………….13
i. Connect the Blast Hose, Compressor Air Hose, and Lines to the Blast Pot…….…………13
ii. Fill the Blast Pot with Abrasive and Water………………………………………..………..14
iii. Turn on the Compressor……………………..………………………………………………15
iv. Pressurize the Blast Pot…………………...…...……………………………..………………15
V. Active Blasting……..…………………………………………...…………………………………..16
Begin Blasting……………………………………………………………………………………..16
VI. Blast Pot Shut Down…………….………………………………………...……………………..17
VII. In Process Adjustments…………….…………...……...……………………...……………………..18
Adjusting Abrasive Flow Rate………………………………………………………...…………18
Increasing media flow…………………………………….………...……….…………….18
Decreasing media flow…………………………………………………………………….19
Adjusting Operating Pressure…………………………………………………………………...19
Adjusting Blast Distance…………………………………………………………………………19
VIII. Transitioning from Wet to Dry Blasting………..……………….…..……………………20

3
IX. Machine Storage……………...……………………………..…………………………………..…21
Storing the Machine in Cold Climate…………..……………………………………………….21
Blasting in Freezing Temperatures…………..………………………………………………….21
Machine Transportation………………………...……………………………………………….22
Moving the Blast Pot…………..…………………...…………………………………………….22
X. Maintenance…………..………………………………..……………………………………………23
Control Box………………………………….……………………………………………………..23
Pressure regulator…………………………………………………………………….…23
Control box Parker valve……………………...……………………………………….…23
Blast Pot Pressure Regulator………………….…………………………………………………..24
Filter Regulator………….……………...………………………………………………………….24
Blast Hose…………….……………………..…………………………...…………………………24
General Blast Pot Maintenance…………….………………...………………………...…………25
Flushing the blast pot…………………………………..…………………………………25
Blast wear parts…………………………………….…..…………………………………26
Pinch Hose Maintenance…………….………………...………………..…………..……………27
Using the pinch hose…………..…………………….…..…………………………………27
Removing the brass couplings from an old hose………….…..………….…………...……28
Attaching the brass couplings to the new pinch hose…….…..…………….………………28
Preventative Maintenance……………...……………...………………..………………………29
Daily maintenance…………..………………...…….…..…………………….……………29
Weekly maintenance………….…..…………………..…………..…………………...….…29
Monthly maintenance…….…..…………………………………………………..….………30
XI. Troubleshooting………………………...…………...………………….…………………………..31
Media Buildup Inside the Blast Pot……………………..………………………………………..31
Adjust the vibrator valve…………..………………….…..…………………………………31
Abrasive Flowing Incorrectly……………………..……..………………………………………..31
Check installation and air pressure……………………...………………….…..……………31
Check media quality………………………………….…..………………….…..……………31
Nothing Coming from the Blast Nozzle……………………..……..……………….……………..31
Pinch Valve is Not Opening or Closing (Electric)…..……..…..……………….……….………..31
Pinch Valve is Not Opening or Closing (Pneumatic)…..……..…..……………….……………..32
XII. Appendix……………………...…..……...…….…………..……………...…………..………...33-36
XIII. Additional Resources……....…….………...……...…………..………………………………..37

4
I. INTRODUCTION
This manual covers the start up, operation, storage, maintenance, and troubleshooting, for a DB500® blast
pot. Intended users must read and understand the contents of the instructions before operating their
machine and its accessories. The intended user should be able to safely operate the blast machine and be
aware of the hazards associated with blasting.
Proper personal protective equipment is required for the operator and any supportive personnel. This
includes but is not limited to hearing protection, eye and face protection, helmet, leather gloves protecting
the full forearm, safety shoes or boots. To protect from dust inhalation, NIOSH-approved air fed
respirators with at least Grade D breathing air is required.
Notice Symbols
For operator safety and machine preservation, please pay careful attention to the special notices listed
in this manual.
A point of emphasis or reminder for operator. Can also indicate potential for
minor problems
Potential for damage to equipment or problems in the outcome if statement is not
closely followed
Note
DANGER
Warning
Caution
Possibility of minor injury to operator or bystanders
Possibility of serious or fatal injury to operator or bystanders
The blast pot is ASME, NB, CE, and/or PED certified. Welding, grinding, or drilling on the pot
voids the National Board certification and manufacturer's warranty. Such actions may affect the
dimensional integrity of the blast pot. The user should install a required safety relief valve to prevent
the rise of pressure no more than ten percent of the set MWP as required by ASME section VIII,
Div. 1. The design maximum and minimum parameters shall not be exceeded. See the parameters in
Figure 1 below. Be sure to read all warnings listed on the blast pot before operation. See Figure 1.1
below for more information.
Figure 1. Name plates Figure 1.1 Blast pot warning label

5
Blast Pot Warranty
MMLJ, Inc. Limited Warranty
Terms of Warranty
MMLJ, Inc. warrants the product you have purchased is free from defects in materials or workmanship under
normal use during the warranty period. Your sales receipt, showing the date of purchase for this product, is your
proof of the date of purchase. This warranty is valid only if the product is assembled/installed according to the
instructions included with the product. This warranty extends only to you, the original purchaser. It is not
transferable to anyone who subsequently purchased the product from you.
During the warranty period, MMLJ, Inc. will repair or replace (at MMLJ, Inc.’s option) the product if it becomes
defective or otherwise fails to conform to this Warranty under normal use. In repairing the product, MMLJ, Inc.
may replace defective part with new, or at the option of MMLJ, Inc., serviceable used parts that are equivalent to
new parts in performance. MMLJ, Inc. reserves the right to change manufacturers of any part to cover any
existing warranty. This extends to items normally covered by a manufacturer other than MMLJ, Inc. used on this
product within the first calendar year of purchase.
This warranty does not cover shipping charges, export taxes, custom duties and taxes, or any other charges
associated with transportation of the parts or products. To obtain warranty service, you must contact MMLJ,
Inc.’s customer service representatives. Any parts determined to be defective must be brought to the attention of
MMLJ, Inc. within six months of delivery of equipment. You must prepay any shipping charges, export taxes,
custom duty taxes, or any other charges associated with transportation of the parts or product. In addition, you are
responsible for insuring any parts or product shipped or returned. You assume the risk of loss during the
shipment. You must present MMLJ, Inc. with proof-of-purchase documents (including the date of purchase). Any
evidence of alteration, erasure, or forgery of proof-of-purchase documents will be cause to void this warranty.
The warranties listed above do not extend to any product that has been damaged or rendered defective (a) as a
result of accident, misuse, or abuse (b) by the use of parts not manufactured or sold by MMLJ, Inc. and/or (c) by
modification or improper installation of the product. Product on which the serial number has been defaced or
removed is not eligible for warranty service. Should any product submitted for warranty service be found
ineligible, an estimate of repair cost will be furnished and the repair will be made if requested by you upon
MMLJ, Inc. receipt of payment or acceptable arrangements for payment. Except, as expressly set forth in this
warranty, MMLJ, Inc. makes no other warranties, expressed or implied. This is the only express warranty
applicable to Dustless Blasting® branded products. MMLJ, Inc. does not assume, nor authorize anyone to assume
for it any other express warranty.
Blast Pot Limited Lifetime Warranty
This warranty applies only to pressure vessels manufactured by MMLJ, Inc. under the Dustless Blasting® brand
name. This product is backed by a limited lifetime warranty, excluding only expendable parts such as gauges and
valves (which are covered by manufacturer other than MMLJ, Inc.) and paint. This Limited Warranty does not
extend to any product that has been damaged or rendered defective (a) as a result of lack of maintenance,
accident, misuse, or (b) abuse by the use of parts not manufactured or sold by MMLJ, Inc. and/or (c) by
modification or improper installation of the product.
Third Party Warranties
For parts that are not covered by MMLJ, Inc., please contact our office and report the defect. MMLJ, Inc. will
then proceed with the warranty process for the affected item on your behalf. All items not covered by MMLJ, Inc.
will fall under a limited one year warranty free of manufacturer defects.
For more warranty information, visit www.DustlessBlasting.com/legal/warranties.
Please call our office for any questions on warranties or warrantied items.
Toll Free: 800-717-5707 International: [phone] Email: [e-mail]

6
Safety Overview
-
Personal Protecve
Equipment (PPE)
Blast pot
Blast pot
Blast hose. Avoid crimping the blast hose when
using. Check the hose for wear before use. Make sure
all safety pins are in place when attaching a blast
hose. Pressure can cause the hose to disconnect and
can inflict serious injury or death.
Protective Equipment (PPE). Follow all OSHA
guidelines for PPE before, during, and after the
blasting process.
Remote controls. Never attempt to bypass the
remote (safety) controls on the blast pot setup. A few
important safety points to ensure are in proper
working condition are the deadman control, pinch
valve, and pinch hose.
Abrasive. Media must be suitable for blasting and
the conditions the operator chooses to blast in i.e. wet
or dry blasting. Do not use abrasives with more than
one percent crystalline silica. Be sure to check an
abrasive’s Safety Data Sheet for more information on
media contents.
Compressor. Air compressor should be properly
maintained and sized to provide adequate CFM for the
tools in use. Excessive compressed air pressure can
cause a blast machine to rupture. Be sure to read and
understand the compressor user manual before use.
Blast pot. The DB500® is designed to blast for
approximately 60 minutes. Inspect the machine,
nozzles, hoses, and couplings before operating. Make
sure to ground the equipment before use to avoid the
risk of electrical shock. Wire all kwik-fit couplings
together. Keep the machine in safe, operable condition.
Read all warnings on the pot before operation.
Air filter. Used with NIOSH-approved respiration
equipment to remove air contaminants. Follow the
manufacturers requirements for replacing these filters as
necessary. Air filter does not detect or remove carbon
monoxide.
Gas monitor. When using a respirator, always be
sure to have a working gas monitor. This helps to
protect against potential for carbon monoxide
poisoning and monitoring levels of other gases, such
as oxygen, with the operator’s NIOSH-approved
respirator.
NIOSH-approved respirator. Respirators can only
give a satisfactory level of protection when they are
selected, fitted, used, and maintained according to the
manufacturer’s written instructions, NIOSH
guidelines, and OSHA requirements. Replace helmet
lens and filters frequently.
Appropriate blast nozzle. Check the nozzle for wear
before use. Be sure the selected nozzle is appropriate
for the amount of air pressure in use.

7
II. ABRASIVES
DANGER: No dust is safe to breathe. Abrasives may contain toxic materials that are
hazardous to persons in the blasting area when inhaled.
Do not use abrasives containing more than one percent crystalline (free) silica. Inhaling
crystalline silica sand can cause silicosis, lung cancer, and breathing problems to exposed
persons.
Slags can contain trace amounts of toxic metals such as arsenic, beryllium, and cadmium
and have the potential to cause lung disease.
Be sure to obtain a Safety Data Sheet (SDS) for the chosen blasting abrasive and identify
the potential for any hazardous substances.
Selecting an Abrasive
Caution:
Use abrasives or media specifically manufactured for blasting. Consider the following information
on choosing abrasives carefully as the type of abrasive can affect blasting efficiency, surface finish,
and machine integrity. Check local environmental guidelines for potential restrictions of certain
abrasive use before blasting. If blasting an unfamiliar surface, test abrasive selection on a small
portion of the surface.
Abrasive shape
Angular. This type of abrasive has irregular edges
that create a textured surface in the blasting
substrate. A textured or anchored surface is ideal
for paint or finishes.
Round. Smooth edges on a rounded shape
abrasive will leave a surface smooth. When the
goal of blasting is to clean a surface without
needing to create texture, a smooth shape will give
the desired profile.
Abrasive size, density, and hardness
Size. Most abrasives, or media, are measured by their
mesh size. An abrasive’s mesh size is defined by the
number of holes in a screen the media can pass through
per square inch. Refer to Figure 2 for a visual
representation of common mesh sizes.
Figure 2. Common mesh sizes

8
Density. Knowing the weight or bulk density of an abrasive can help an operator choose the
appropriate abrasive for the job. The density is measured in pounds per cubic foot, so an
abrasive with a bulk density of 75 lb/ft3 is less dense than a sample of 145 lb/ft3. The higher
the bulk density, the more impact the abrasive will have on the blasted surface.
Note: Choosing a coarser media will not always increase productivity. The user should
consider mesh size, density, and hardness of an abrasive when factoring productivity and
end surface goal.
Hardness. Generally, a harder abrasive will impact the blasted surface profile more than a
softer abrasive. A softer media, such as organic materials and plastics, is sufficient for
removing dirt, oil, grease, and paint without damaging the target surface. An abrasive’s
hardness may be measured in a couple ways. A common quantitative figure comes from the
Mohs hardness scale. The media will fall on a scale of 1-10. 1 being the softest media and
10 being the hardest.
Media Comparison Charts
Description Bulk
Density Hardness Surface Profile Surface Removal Velocity
Sugar Sand Round media used for cleaning
and stripping 100 lb/ft36 – 7 High etch Yes Medium fast
Sodium
Bicarbonate
Medium-sized abrasive, creates
a smooth surface when
stripping 61 lb/ft32.5 No etch No Slow
Walnut
Shells
Angular, organic for mildly
powerful stripping without
damage to the blast surface 50 lb/ft34.5 – 5 Low etch Very slight Medium
slow
Corn Cob Organic, soft media ideal for
soft surfaces like wood 40 lb/ft34 – 4.5 No etch No Slow
Selecting the appropriate abrasive for the job is important to maintain efficiency, conserve
media, and protect the integrity of the blasted surface. Figure 3 and Figure 4 below show a few
examples of potential media an operator may choose to use. Dry blasting specific media cannot
be used in wet blasting as the listed abrasives do not sink in water, a key parameter for successful
wet blasting.
The below figures are arranged from most dense to least dense media. Additionally, each
abrasive has a listed hardness value, surface profile, surface removal ability, and velocity (how
fast or slow the media travels from the blast pot) description.
Figure 3. Dry Blasting Abrasive

9
Description Bulk
Density Hardness Surface Profile Surface Removal Velocity
Steel Grit Angular for fast
stripping and aggressive
cleaning
260 lb/ft340 – 65
HRC High etch Moderate Medium fast
Steel Shot Spheres designed for
polishing and peening 230 lb/ft340 – 51 HRC No etch No Medium
Aluminum
Oxide
Sharp, long lasting
media for fast etching
and profiling 110 lb/ft38 – 9 High etch Yes Fast
Blast Sand Angular, sharp edges to cut into the surface and
leave an anchor profile 100 lb/ft37High etch Yes Medium
fast
Crushed
Glass
Free from crystalline
silica, 100% recycled
glass, efficient, cost-
conscious
100 lb/ft35 – 6 Medium-
high etch Slight Fast
Glass
Beads
Round, soda-like glass
produces a bright, satin
finish. 95 lb/ft35 – 6 No etch Slight Medium
fast
Silicon
Carbide
Hard, powerful cutting
media, ideal for stone,
glass, and tough
surfaces
90 lb/ft39 – 9.5 Very-high
etch Yes Very fast
Garnet Angular, hard media
commonly used in place
of silica sand 85 lb/ft37.5 – 8.5 Very-high
etch Yes Very fast
Coal Slag
Angular byproduct of
coal, used for removal
of coatings from steel
and concrete
85 lb/ft36 – 7 High etch Yes Medium
fast
Plastic
Abrasives
Soft media for
automotive and
aerospace applications
50 lb/ft33 – 4 No etch Slight Medium
Figure 4. Wet or Dry Blasting Abrasive

10
Abrasive Fill Levels
Note: The DB500® has a maximum hold of:
• 20 gal of clean water
• 200 lb of abrasive (~40/70 mesh
size)
• 28 oz of Rust Inhibitor
The blast pot does not require a maximum fill for operation. If the maximum fill is not needed for a job,
fill the machine according to estimated blast time. Use Figure 5 below for an approximate reference.
Figure 5. Fill guide for blast pots

11
III. PREPARING TO BLAST
Personal Protective Equipment
DANGER: Failure to maintain proper PPE can result in the serious injury or death of
the operator or bystanders. Loud noise generated by blasting can cause hearing
damage. Everyone in the area must use proper hearing protection. It is the employer’s
responsibility to train employees to identify hazardous substances and to provide
suitable policies, procedures, monitoring, recordkeeping, and PPE.
The Occupational Safety and Health Administration (OSHA) recommends abrasive blasting
operators wear the following PPE while working:
• Hearing protection
• Eye and face protection
• Helmet
• Leather gloves that protect to full forearm and aprons (or coveralls)
• Safety shoes or boots
Additionally, operators and support personnel in the blasting area should wear proper respiratory
protection.
Respirators should:
• Cover the head, neck, and shoulders
• Be approved by the National Institute for Occupational Safety and Health (NIOSH)
DANGER: Breathing air must meet OSHA class D standards. Using a breathing air
source that does not meet class D standards can cause asphyxiation and death. Be sure
to use a high-temperature alarm and carbon monoxide monitor. Always make sure the
respirator hose is not connected to a line that supplies non-breathable gasses. Before
breathing air, be sure to test the content of the respirator line. Failure to follow these
procedures can result in serious injury or death to the user.
Masking and Containment
Masking
Cover or mask off items such as glass, chrome, rubber seals, wiring, electrical, or moving mechanical
parts that look delicate or should remain clean and dry. Tape is a good solution for covering small
pieces and parts.
Containment
Capture the blasting byproducts using a heavy tarp. Be sure to weigh down the corners of the tarp for
efficient containment.

12
Model DB500®
The figures below show commonly referenced parts of the DB500® blast pot mentioned in this manual.

13
IV. BLAST POT START UP
i. Connect the Blast Hose, Compressor Air Hose, and Lines to the Blast Pot
Attach the blast hose to the pinch hose
at the top of the blast pot and insert the
safety pins.
Caution:
When selecting the most productive
nozzle for the job, there are two
main points to consider. Check
what volume of air the compressor
in use can supply per minute
(CFM) and the desired nozzle
pressure (PSI) to maintain during
blasting. Be sure to choose the
appropriately sized nozzle for a
specific compressor and job to
avoid unnecessary damage to the
equipment or blasted surface.
Pneumatic blast pot. Fasten the twin line
to the control box
Connect the compressor air hose to the
compressed air inlet and insert the
Note: Be sure to connect the twin
line to the control box matching red
to red and green to green
Electric blast pot. Connect the electric line
of the red head controller to the control box
on the back of the blast pot.
Screw on the appropriate blast hose
nozzle. The nozzle size is based on the
air compressor size.
Safety pins

14
ii. Fill the Blast Pot with Abrasive and Water
DANGER: Do not use abrasives with more than one percent crystalline silica.
Breathing crystalline silica dust can cause silicosis, a potentially fatal and damaging
lung disease. Refer to the abrasive’s Safety Data Sheet (SDS) to identify potentially
toxic substances in the media. Always wear appropriate NIOSH-approved
respirators throughout the blasting process to help prevent potential serious injury
or death.
Do not attempt to remove the fill cap on a pressurized machine.
Place the fill funnel into the pot
opening and pour in a premeasured
amount of clean water.
Caution:
Use the provided media filter to
reduce the likelihood of clogging.
Debris in the system can damage
the machine.
Pour in a predetermined
amount of abrasive.
Remove the funnel and replace
the fill cap.
Note: For detailed information on
choosing the appropriate abrasive type
and amount for the job, see section II of
this manual.
Note: If Rust Inhibitor® is needed, add it
to the blast pot at this time.
Remove the fill cap by pulling up on
the fill cap handle and turning the cap
counterclockwise

15
iii. Turn on the Compressor
Caution:
Reference the instruction manual for the selected compressor model before operating.
Allow the compressor to idle and warm up for about 15-30 seconds.
Slowly open the air inlet-shutoff valve.
Caution:
Pressurize the blast pot before starting the active blasting process. When the machine pressurizes, the
abrasive lever on the blast pot will pop up. Adjust the operating pressure based on project goals. For more
information on tuning blast pressure, see subsection “Adjusting Operating Pressure” on page 19 of this
manual.
Open the air inlet-shutoff valve slowly to prevent damage to the machine from too much compressed air
flowing in at one time. The air inlet-shutoff valve and the blow down valve will be in opposite positions.
iv. Pressurize the Blast Pot
Pull up on the abrasive lever to move the
handle into the unlocked position.
Close the blow down valve. To prevent build up of moisture, loosen the
screw at the bottom of the filter regulator
on the left of the control box and slightly
open the moisture trap valve.

16
V. ACTIVE BLASTING
Danger: Uncontrolled blast stream and high-velocity abrasive particles can inflict serious
injury. Always maintain nozzle control and point the blast nozzle in the direction of the
blast surface only. Make sure the blast hose is securely fastened to prevent detaching
during operation. Keep unprotected workers out of the blast area.
Ensure proper PPE is secure and in place.
Never attempt to bypass the safety controls on either the pneumatic or electric blast pot.
Do not leave a blast pot unattended. If there is an emergency, shut the machine down
immediately.
Warning:
To avoid injury to the operator and damage to the machine, check the pinch hose is properly
maintained before beginning the active blasting process. Use caution when connecting power to
an electric blast pot control.
Begin Blasting
Note: For best results, try different blast patterns and angles to find the proper workflow.
Adjust the vibrator valve so the blast pot is at maximum vibration.
Check the abrasive lever is still in the unlocked position.
Make sure the operating pressure is adjusted for optimal project-based performance.
Start the active blasting process. Based on the type of blast pot, the handle activation will vary.
See the diagrams below and follow the instructions based on the type of handle included with the
pot.
Electric blast pot handle. Slowly
press the toggle switch of the redhead
electric deadman controller.
Pneumatic blast pot handle. To activate the
blast hose, depress the safety button on the side
of the deadman controller and slowly press the
handle on the top of the control.

17
VI. BLAST POT SHUT DOWN
Caution:
DO NOT turn off the compressor when starting the shut down process. Failure to leave the
compressor running will cause a backflow of air, water, and media into the system and damage the
machine.
Let the pot fully depressurize before
turning off the compressor.
While the compressor is running, close the
air inlet-shutoff valve.
Open the blow down valve to
release the pressure in the blast pot.

18
VII. IN PROCESS ADJUSTMENTS
There are three recommended areas of adjustment to aid in an efficient blasting process.
• Abrasive flow rate
• Blasting pressure
• Stand-off distance
Adjusting Abrasive Flow Rate
The desired flow rate of media from the blast pot may change from surface to surface. There
are adjustments that can be made throughout the blasting process to maximize media flow
rate.
Increasing media flow
Increase the amount of abrasive in the
blasting output by turning the abrasive
valve in quarter-turn, counterclockwise
increments.
Note: Each quarter turn raises the outlet
pipe 1/16” of an inch, allowing more
media and water to flow from the blast
pot. Once the desired result is achieved,
secure the outlet pipe in place with
the locking nut.
Note: The media flow rate has been
fully adjusted once the removal rate
fails to increase.
Make sure the abrasive lever is all
the way down in the locked
position.
Test the effectiveness of each
quarter turn on the blasted surface.
Caution:
Do not bypass the safety sleeve when
adjusting the height of the outlet
pipe.

19
Decreasing media flow
Fully depressurize the blast pot
before decreasing media flow.
Decrease the amount of abrasive in
the blasting output by turning the
abrasive valve in quarter-turn,
clockwise increments.
Adjusting Operating Pressure
Finding the optimal pressure is important for maximizing operator efficiency while protecting the
blasted surface.
To adjust the pressure:
• Rotate the pressure regulator knob clockwise to increase the pressure.
• To lower the pressure, rotate the pressure regulator knob counterclockwise.
Note: When lowering the pressure while the blast tank is pressurized, be sure to release some
pressure by blasting the excess or opening the blow down valve slightly until pressure is released.
Adjusting Blast Distance
The distance the operator holds the blast nozzle from the targeted surface affects the power, speed,
and blast pattern of the job. Holding the blast nozzle too far from the work surface will create a larger,
less efficient pattern. Inversely, the nozzle too close to the blasted surface will give a small, overly
powerful blast pattern.
Find the right balance between blast pattern and removal speed by adjusting how close or far the blast
nozzle is to the work surface.
Note: Adjust the blast nozzle so the media stream is hitting the surface at a 45-degree angle for a
more efficient technique.

20
VIII. TRANSITIONING FROM WET TO DRY BLASTING
Caution:
The DB500® is suitable for wet and dry blasting. To dry blast, an air drying and cooling system is
required.
To prepare the blast pot for dry blasting:
1. Blast all media and water out of the machine.
2. Remove the fill cap.
3. Connect the air cooling and dryer system to the compressor and turn on the fan.
4. Open the air inlet-shutoff valve halfway and let the air circulate through the blast pot for
five to seven minutes, or until completely dry.
5. Place the fill cap back in the blast pot and pressurize the tank.
6. Run air through the machine as if blasting for two to three minutes.
7. Inspect the pot’s tank to make sure there is no residual moisture.
8. Once all moisture is gone, fill the blast pot with one bag of dry blasting suitable abrasive.
Note: See the manual for the selected air
drying and cooling system for more
information on start up/shut down
procedures.
Caution:
Turn the vibrator valve off on the blast pot when dry blasting to avoid media clogging
at the bottom of the machine.