S Programmable Salt Spray Fog Chamber
The salt spray test is a standardized test method used to check corrosion resistance of coated samples. Coatings provide corrosion resistance to metallic parts made of steel, zamak or brass. Since coatings can provide a high corrosion resistance through the intended life of the part in use, it is necessary to check corrosion resistance by other means. Salt spray test is an accelerated corrosion test that produces a corrosive attack to the coated samples in order to predict its suitability in use as a protective finish. The appearance of corrosion products (oxides) is evaluated after a period of time. Test duration depends on the corrosion resistance of the coating; the more corrosion resistant the coating is, the longer the period in testing without showing signs of corrosion.
Salt spray testing is popular because it is cheap, quick, well standardized and reasonably repeatable. There is, however, only a weak correlation between the duration in salt spray test and the expected life of a coating (especially on hot dip galvanized steel where drying cycles are important for durability), since corrosion is a very complicated process and can be influenced by many external factors. Nevertheless, salt spray test is widely used in the industrial sector for the evaluation of corrosion resistance of finished surfaces or parts.
The apparatus for testing consists of a closed testing chamber, where a salted solution (mainly, a solution of 5%sodium chloride) is atomized by means of a nozzle. This produces a corrosive environment of dense saline fog in the chamber so that parts exposed in it are subjected to severely corrosive conditions.
Tests performed with a standardized 5% solution of NaCL are known as NSS (neutral salt spray). Results are represe-nted generally as testing hours in NSS without appearance of corrosion products (e.g. 720 h in NSS according to ISO 9227). Other solutions are acetic acid (ASS test) and acetic acid with copper chloride (CASS test), each one chosen for the evaluation of decorative coatings, such as electroplated copper-nickel-chromium, electroplated copper-nickel or anodized aluminium.
Some sources do not recommend to use ASS or CASS test cabinets interchangeably for NSS tests, as it is claimed that a thorough cleaning of the cabinet after ASS or CASS test is very difficult. ASTM does not address this issue, but ISO 9227 does not recommend it and if it is to be done, advocates a thorough cleaning.
Biuged offer various Salt Spray Cabinets from 150L capacity to customized cabinets according to different requirements. All of cainets not only can run NSS test but also CASS or ASS test
Standards
- ISO 4611 – Plastics — Determination of the effects of exposure to damp heat, water spray, and salt mist
- ISO 7253 – Paints and varnishes — Determination of resistance to neutral salt spray (fog)
- ISO 9227 – Corrosion tests in artificial atmospheres — Salt spray tests
- ASTM B117 – Standard Practice for Operating Salt Spray (Fog) Apparatus
- ASTM B368 – Standard Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)
- ASTM B380 – Standard Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
- ASTM G85-11 – Standard Practice for Modified Salt Spray (Fog) Testing
- ASTM D1735 – Standard Practice for Testing Water Resistance of Coatings Using Water Fog Apparatus
- DIN 50021 – Salt Spray Testing
1.0 Structure Feature
| Component | Description |
|---|---|
| Chamber Structure |
- Cabinets made of imported 1.5mm PVC plate (Nanya, Taiwan), max temperature 85°C. - Sealing cover made of European Form acrylic sheets. - Salt solution reservoir with water level design, easy to clean. - Humidifying tower made of SUS 304, high pressure resistance, good insulation. - Adjustable specimen support angle for uniform fog. - Uses water to seal the working room. - Electric system isolated from water system. - Drain outlet diameter 48mm at back and bottom. |
| Chamber Sealing Cover | V shape, top angle is 100°, prevents condensate from dropping on specimen. |
| Atomizing Tower | Glass nozzle atomizes salt solution; uniform fog via atomizing tower. |
| Fog Collector | Funnel-shaped, diameter 100mm, installed at bottom; connected to external graduated cylinders. |
| Heating System | Uses titanium alloy; steam heats chamber from bottom. |
| Salt Solution Supply | Reservoir-fed via level difference; auto water leveling device included. |
| Humidifying Tower | SUS304 steel; temp from RT to 63°C; 60 min heat-up time; auto water addition & monitoring. |
| Heater | Armored titanium alloy heating tube (bottom of chamber); SSR-controlled. |
2.0 Fog Spray System
| Component | Description |
|---|---|
| Spray Fog Principle |
Bernoulli’s principle used to atomize salt solution. Flow: Air Compressor → Water Separator (1st) → Air Tank → Relief Valve → Total Solenoid Valve → Water Separator (2nd) → Saturator → Pressure Regulating Valve → Solenoid Valve for spraying. |
| Spray Nozzle | Made of special glass, can control fog amount and spray angle. |
| Spray Pressure | Adjustable from 0.07MPa to 0.17MPa in two steps: - Step 1: 0.02MPa to 0.04MPa - Step 2: 0.07MPa to 0.17MPa |
3.0 Electronic Control System
| Component | Description |
|---|---|
| Drain away Fog | Manual or timed; fresh compressed air fed to working room to remove fog quickly. |
| Controller | ESCC digital temperature controller (Omron, Japan); controls working and humidity temperatures. |
| Working Method | Fixed value mode; start/stop is timed. |
| Setting Method | English menu; input via keyboard. |
| Display Resolution | 0.1°C |
| Timer | Digital display in sec/min/hour: Max: 9,999 hours, Min: 1 sec |
Main Technical Parameters
| Parameter | Specification |
|---|---|
| Working Room Temperature Range | RT ~ 50°C |
| Humidifying Tower Temperature Range | RT ~ 63°C |
| Temperature Uniformity | ± 2.0°C (No Load) |
| Temperature Stability | ± 0.5°C |
| Temperature Deviation of Working Room | ± 1.0°C |
| Temperature Increasing Rate | RT→55°C: less than 60 minutes (working room) RT→63°C: less than 80 minutes (saturated barrel) |
| Compressed Air Supply | 0.4MPa ~ 0.8MPa (clean, oil-free, dry air) |
Ordering Information
| Parameter | BGD 880/S | BGD 881/S | BGD 882/S | BGD 883/S |
|---|---|---|---|---|
| Working Room Size (W×H×D, mm) | 600×400×450 | 900×600×500 | 1200×500×800 | 1600×500×1000 |
| Working Room Capacity (including V shape cover) | 108 L | 270 L | 480 L | 800 L |
| V Shape Cover Volume | Approx. 50 L | Approx. 250 L | Approx. 380 L | Approx. 480 L |
| Overall Size (W×H×D, mm) | 1150×910×1020 | 1350×1240×1040 | 2480×1240×1250 | 2480×1450×1250 |
| Sample Holder Size (mm) | 816 | 1022 | 1042 | — |
| Tank Capacity for Salt Solution | 45 L | 45 L | 75 L | 100 L |
| Collectors | 2 | 2 | 4 | 4 |
| Max. Sample Capacity (150mm × 70mm) | 108 pcs | 120 pcs | 120 pcs | 120 pcs |
| Method of Opening Cover | Pneumatic | |||
| Total Power | 2.2 kW | 3.8 kW | 3.8 kW | 5.2 kW |
| Salt Solution Consumption | 2.5 L/d | 2.5 L/d | 2.5 L/d | 2.5 L/d |
| Water for Heating Consumption | 30 L/d | 40 L/d | 40 L/d | 60 L/d |
| Compressed Air Consumption | 0.5 m³/h | 2 m³/h | 2 m³/h | 2 m³/h |
| Power Supply | 220V; 50/60Hz | |||
