Salt Spray tester Vexus SST series
Brief Introductions:
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, 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 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 attacked under this severe corroding atmosphere.
Typical volumes of these chambers are of 15 cubic feet (420 L) because the smallest volume accepted by ASTM-B-117, ISO 9927 (400 liters) and now discontinued DIN 50021 (400 liters). It has been found very difficult to attain constancy of corrosivity in exposure regions within the test chambers below 400 liters. Chambers are available from sizes as small as 9.3 cu ft (260 L) up to 2,058 cubic feet (58,300 L), most common machines range from 15 to 160 cubic feet (420–4,500 L).
Tests performed with a standardized 5% solution of NaCl are known as NSS (neutral salt spray). Results are represented generally as testing hours in NSS without appearance of corrosion products (e.g. 720 h in NSS acc. 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 recommended 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.
Chamber construction, testing procedure and testing parameters are standardized under national and international standards, such as ASTM B 117 and ISO 9227. These standards describe the necessary information to carry out this test; testing parameters such as temperature, air pressure of the sprayed solution, preparation of the spraying solution, concentration, pH, etc. Daily checking of testing parameters is necessary to show compliance with the standards, so records shall be maintained accordingly. ASTM B 117 and ISO 9227 are widely used as reference standards. Testing cabinets are manufactured according to the specified requirements here.
However, these testing standards neither provide information of testing periods for the coatings to be evaluated, nor the appearance of corrosion products in form of salts. Requirements shall be agreed between customer and manufacturer. In the automotive industry requirements are specified under material specifications. Different coatings have different behavior in salt spray test and consequently, test duration will differ from one type of coating to another. For example, a typical electroplated zinc and yellow passivated steel part lasts 96 hours in salt spray test without white rust. Electroplated zinc-nickel steel parts can last more than 720 hours in NSS test without red rust (or 48 hours in CASS test without red rust) Requirements are established in test duration (hours) and coatings shall comply with minimum testing periods.
Instrument Features:
LCD touch screen controller supports the continuous and intermittent texting
Refilling water automatically when water level is insufficient.
The whole part of the device is made of Excellent PVC sheet and the inside of the device is reinforced by using a special lining material. Hence, it is sturdily made and will not transform forever.
The test chamber is heated from five directions in order to ensure the temperature difference in the chamber must be kept within±1 Celsius degree.
Spray nozzle: The nozzle is specially made to enable it to suck up the salt Water and then spray it out in the shape of mist with considerable high speed. When it falls on the surface of the item being tested , the difference of fallen mist must be controlled within±0.3ml per 80 square centimeter H.
HUNTER PRINCIPLE is used to make the saturated air hot and moist and to keep the humidity in the test chamber required for test.
Temperature is the pre-requisite condition that will have direct impact on corrosion rate . We use PID temperature control unit to limit the temperature difference within the range of ±1 Celsius degree.
Salt Spray tester Vexus SST seriesTechnical Specifications
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Mode
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Vexus SST-60T
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Vexus SST-90T
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Vexus SST-120T
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Vexus SST-160T
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Vexus SST-200T
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Order#
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221*111
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221*121
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221*131
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221*141
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221*151
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Inside Dimensions(mm)
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600x450x400
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900x600x500
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1200x850x500
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1600x1000x550
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2000x1200x600
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Outside Dimensions(mm)
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1130x630x1070
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1460x910x1280
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2200x1200x145
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2600x1450x1550
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3000x1650x1600
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Chamber Volume
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108L
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270L
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480L
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800L
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1440L
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Saline Box Capacity
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15L
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25L
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40L
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40L
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40L
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Testing Temperature
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NSS ACSS 35℃±1℃/ CASS 50℃±1℃
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Air Temperature
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NSS ACSS47℃±1℃/CASS 63℃±1℃
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Accuracy of Temperature
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±1℃
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PH Value
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NSS ACSS:6.5~7.2 / CASS:3.0~3.2
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Supply Power
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AC220V/50Hz AC110V/60Hz 1Φ20A
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AC 220V/50HZ AC110V/60HZ 1Φ30A
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Standard Delivery
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Quantity
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Standard Delivery
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Quantity
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Power cable
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1PC
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PVC V-shape bracket
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1SET
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Wet inductive cotton
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5 PCS
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Φ10mm glass rod
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1SET
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5M soft inlet and outlet water pipe
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1PC
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9.5L Salt water mixer
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1 PC
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3M soft exhaust pipe
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1PC
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Operation manual
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1 COPY
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In accordance with:
ASTM B117
ISO9227
NSS ACSS / CASS
Optional Accessories
Air Compressor
Reagent : NaCl