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SnowBox™ Dry Ice Cleaning Station

SnowBox™ Dry Ice Cleaning Station
SnowBox™ Dry Ice Cleaning Station
  • Provides a dry, inert environment to prevent moisture condensation when cleaning with dry ice
  • Durable 304 stainless steel glove box ensures a clean processing environment
  • Optional air locks provide separate entrance/exit ports
  • Tilt-up window and built-in quick connect CGA 320 fitting allows easy connection of SNO GUN™ II
  • Includes fluorescent illuminator

The SnowBox™ Dry Ice Cleaning Station provides the ideal environment for operation of the SNO GUN™ II dry ice cleaning system.

Because the dry ice cleaning medium is extremely cold, it can cause the temperature of parts to drop beneath the dew point of the ambient air. In a humid environment, this will lead to moisture condensation that can contribute to oxidation or other contamination problems.

Automatic Moisture Control
The SnowBox™ Dry Ice Cleaning Station prevents these problems by maintaining a dry nitrogen environment. Nitrogen flow is controlled in two ways. The Dual Purge™ System provides a low-level nitrogen flow to maintain a continuous positive pressure inside the enclosure. When an air lock door of the tilt-up window is opened, it automatically activates a high-level flow, which helps to block out moisture influx and quickly remove any moisture that may enter the chamber.

The optional NitroWatch™ system provides additional moisture control by allowing you to determine a humidity set point down to 0% RH. If the internal humidity level climbs above this setpoint, the NitroWatch sends a signal to the Dual Purge System to activate the high-level purge. Moisture and CO2 are purged out of the cabinet through Automatic RB® (relief/bleed) valves, which guard against overpressures.

Convenient Pass-Through Access
Terra's air locks provide a convenient, noncontaminating way to move parts in and out of the glove box.

Knife edges along each access door seal against inlaid polyurethane gaskets to form an air-tight seal. Double-wall stainless steel construction, with heavy-duty door latches and hinges, ensures a long service life. Ports are included for nitrogen purging. Two Automatic RB® Valves ensure safe pressure release.

The front Tilt-Up Window swings open for easy access to large parts or for installation and connection of the SNO GUN™ II. Dual piston mechanisms hold the window securely open. A static-disipative PVC window allows full view of the internal chamber.

The SnowBox™ Glove Box also includes a quick connect fitting for CO2 line required by the SNO GUN™ II. A fluorescent illuminator is also standard. Options include an ionizing bar, stand, and accordion sleeve/glove assembly.

Specifications
Door Openings: 12.5" x 12.5" (318 mm x 318 mm) with gasketed doors supplied with air locks; doors open inward
Arm Ports: 9" (229 mm) round with flange for connecting glove assembly
Gas Ports: Tapped .75" (19 mm) NPT inlet (for connecting flowmeter or Dual Purge System). Includes two automatic RB Vales for safe pressure release. Appropriate adapter inserts are supplied for any Terra gas systems ordered.

SnowBox™ Dry Ice Cleaning Station

Glove Ports
in. (mm)
A D E F G H I M N
2 16.5
(419)
24
(610)
27.69
(703)
35
(889)
12.38
(314)
28
(711)
16
(406)
14.5
(368)
10
(254)
Also available with other air lock configurations.
 
Ordering Information

SnowBox™ Glove Box

(includes two Relief/Bleed valves, plus one per lock)

Cat. # Price
No Air Lock 1600-87 Price
Right-Side Air Lock 1600-88A Price
Left-Side Air Lock 1600-89A Price
Dual Air Locks 1600-90A Price
Dual Purge System
Cat. # Price
1603-57 Price
Nitrowatch®

Cat. # Price
Control Module 9500-00A Price
Sensor 9500-02A Price

Ionizing Blower
Provides even ion distribution throughout chamber.

  Stand
Fabricated of all-welded 1.5" (38 mm) square tubes. Raises chamber 30" (762 mm) above floor, add 3" (76 mm) for casters.

Cat. # Price
Epoxy-finished steel 1690-03 Price
Stainless steel 1694-09 Price
Heavy-Duty Casters (set of 4, 2 with brakes) 1700-44 Price

Accordion Sleeve and Glove Assembly
Accordion neoprene sleeve section allows easy arm motion and prevents sleeve blow-back when box is under pressure. Separable gloves allow operators to change glove materials or sizes without removing sleeves. Supplied with pair of nitrile industrial gloves (select desired size).

Changeable Sleeve and Glove Combination
Glove Size With 18" (457 mm) Sleeve
Cat. # Price
8 1689-46 Price
9 1689-47 Price
10 1689-48 Price

 

Why Dry Ice Cleaning?
SnowBox™ Dry Ice Cleaning Station Aluminum Oxide Particles
on a Silicone Wafer
SnowBox™ Dry Ice Cleaning Station After Blowing with
Dry Nitrogen
After Blowing with
SNO GUN™II

. . . Because particles in the 1 – 2 micron size range and smaller are difficult if not impossible to remove by conventional blowing with compressed air or dry nitrogen gas.

Such micro-particles are held to the surface not only by electrostatic attraction, but also by bonding forces in the surface layers of absorbed water and organics that are typically integral to the substrate surface. Small particles have a larger percentage of their total surface area in contact with these surface layers, thus giving them greater adhesion. Less of their surface is exposed to any aerodynamic drag forces generated by a nitrogen gun, DI water gun, or other flow of gas or liquid.

Aside from these adhesive forces, small surface contaminants are difficult to remove due to the boundary layer phenomena: a fluid flow (gas or liquid) is only effective at some finite distance away from the surface being cleaned. At the surface itself, the flow velocity must be zero, thus reducing the chance that small particles in the boundary layer will feel the full force of the flow and may not be removed.

Dry Ice Cleaning—Sandblasting Without the Mess! One way to remove these very small contaminants is to introduce a mass into the cleaning flow, thereby penetrating the boundary layer, transferring energy to the contaminant and knocking it off the surface. The challenge is to perform this sandblasting without damaging the delicate part or generating further contaminant residue.

This is precisely what a dry ice cleaning system does. Frozen carbon dioxide particles meet all the requirements for high precision cleaning of delicate components: they are soft and leave no residue, when supplied with precision-grade CO2.

When liquid CO2 is released from a room temperature cylinder to atmospheric pressure, it passes through its triple point—the state at which some portion exists in solid, liquid, and vapor phases. The liquid and vapor quickly dissipate with no net effect on the environment, but the solid dry ice "snow" is directed toward the surface to remove the particles. Nozzles supplied with SNO GUN™ II are used to adjust the dry ice particle size and the shape of the spray pattern to fit a wide variety of applications.

Effective as a Hailstorm or as a Gentle Snow
Typical dry ice particle sizes are in the 5 micron range, which produce a rather aggressive "hail storm," but they can be adjusted in size to about 0.5 cm where they produce a very gentle snowfall effect for cleaning the most delicate surfaces.

At higher velocities (up to 1000 fps) the CO2 not only removes particles, but also dissolves thin organic layers of oils and fluxes—even fingerprints. This solvent action is due to a thin layer of liquid CO2 that forms at the collision interface between a dry ice particle and the surface. Liquid CO2 is an excellent solvent for organics. The very short duration of a liquid film at the interface dissolves the organic film contaminants, which are then carried away in the flow of CO2 snow and vapor. The liquid state of the CO2 also reduces the impact stress on the surface and permits thorough cleaning without destructive forces.

At lower velocities, larger flakes settle on contaminants and lift them off the surface in the process of sublimation to the vapor state—without disturbing delicate substrates. As the dry ice particle sublimes, it creates a micro-explosive expansion that dislodges contaminants.

Dry Ice Cleaning and Thermal Shock
Although dry ice has a temperature of -109.3°F (-78.5°C) at atmospheric pressure, it rarely poses a threat, even to extremely sensitive micro-components.

This is because the sublimation process occurs so quickly, and the mass of the CO2 particles is so small relative to that of the components being cleaned, that brief spraying will not cause significant drop in surface temperature. At high ambient humidity, however, even relatively small temperature drops can lead to condensation of water vapor. In these applications, a dry nitrogen environment can prevent moisture-related damage.

Preventing Moisture Contamination
If cleaning causes the temperature of the parts to drop beneath the dew point of the ambient air, moisture will collect on the parts being cleaned. In many applications, this condensation could lead to oxidation or other contamination problems.

For these applications, Terra recommends cleaning in a nitrogen-purged dry box. At the much lower dew point inside such a chamber, parts will remain dry even if dry ice cleaning does cause small, temporary temperature drops.

Protecting Against ESD (Electro-Static Discharge)
Although CO2 is itself non-conductive, the dry ice particles can generate friction as they leave the nozzle of the SNO GUN™ II, leading to potentially hazardous static charge build-ups. One solution to this problem is grounding ESD-sensitive parts. Another is to direct a convergent stream of ions at any static-sensitive surface. Terra’s Ionizing Air Gun provides this ESD protection, and can be configured to work in tandem with the SNO GUN™ II.

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