Washdown is a fairly common term in the industrial world, though its meaning can differ from industry to industry. Your car is washdown – your cell phone generally is not. Scales and balances called washdown are typically somewhere in between these two examples. So what makes a scale cleanable or washdown for your operational requirements?
Whether your guidance mandates are cGMP, GMP, GLP or any other GxP, your scales and balances must be cleanable to some degree. Whether your operational cleaning procedures are for sanitization, safety, good housekeeping or all of the above, your scales and balances must be cleanable in some way. In the food and pharmaceutical production industries sanitation means washdown with high pressure, very hot water and harsh cleaning agents. In other industrial uses a scale may be considered washdown if it can be cleaned with a hose and a bucket of soapy water. In a lab it may be enough to have removable pans, draft shields and cleanable surfaces in the sample area.
Washdown – It must be engineered from the ground up
Washdown environments should not affect the life of a scale, as the scale should be designed to handle it. Proper material choice, even down to nuts, bolts and washers, is important for long life without corrosion or failure. To make a scale that will survive the hose and soap, the manufacturer must first consider how washdown requirements could affect the electronics, sensors, displays, power, enclosure penetrations and connectors. Generally, this means everything must be sealed to prevent water and cleaning chemicals from getting in. The best engineering, consistent with the desired IP or NEMA rating, is applied to the seal for all enclosures and penetrations. Seal material is likewise chosen to survive specific conditions during washdown. Next, the metals and plastics that will be exposed to water, heat, and cleaning agents must be chosen to tolerate cleaning and also to resist later corrosion. Special care is taken to keep surfaces smooth and minimize entrapment areas. Stainless steel is the metal of choice for washdown applications. Plastics should be high quality, like ABS with additives and inhibitors, which are proven rugged for most harsh environments.
Removable Platforms – May avoid some need for washdown
Removable platforms or adjacent surfaces in the sample area are an important cleanup feature for any scale or balance. This is beneficial also for industrial scales in production use. For sample area cleanup it may easier to remove the platform – typically stainless steel – for a robust cleaning away from the scale. This feature may avoid the need for a full scale washdown after spills. The removable platform will also simplify cleaning by allowing direct access to lower structures under the platform for periodic spot cleaning.
Plastic dust covers – Helpful but not a solution
Some manufactures provide dust covers of heavy gauge plastic to protect the display indicator in normal use. The covers may also provide some protection during wipedown cleaning but should not be relied on for thorough cleaning. Even a small pinhole can leak enough to wet a switch or connector or permanently damage an unprotected display. Damage may not be immediately apparent but could appear later from corrosion effects.
Certifications – IP and NEMA Ratings
Scales designed for washdown applications are frequently certified to industrial standards such as IP 65, IP 66, 67, etc. – and NEMA-4X. There is no government requirement to certify a washdown scale. Washdown is not a technical specification – just a descriptive term. Manufacturers certify their products to IP or NEMA ratings because customers, industries and markets demand proof of product suitability. Testing and certification to a known standard such as IP or NEMA is the only firm basis for judging how well a scale will survive your required washdown conditions.
Caution – Sometimes IP and NEMA certification is only partial
IP and NEMA certifications do not need to apply to the entire scale to be applied to equipment. Components can be certified, such as the platform but not the display. In an industrial hose-down it is likely everything will get wet to some degree. Some manufactures call their scales partial washdown or semi washdown. The value of component only IP or NEMA rating must be judged for each industrial use, taking into consideration accepted good practice, regulatory requirements and the care given by the least capable operator.
Conclusion – Look beyond Washdown to be sure you get what you need
So washdown is many shades of grey. And even IP and NEMA ratings may be questionable if the entire scale is not rated. Practically all washdown means in the scale and balance market is someone – possibly not a scale and balance or industry expert – thought the scale had enough features to be called wet cleanable in some industrial uses. For most industrial customers – that is not enough assurance.
The industrial scale buyer should look to washdown classification only to narrow down the choices. Look beyond the manufacturer’s washdown classification for the relevant certifications, exposed material choices, and removable components, matching your application, industry, mandates and cleaning operation with those of the scale or balance. Understand your needs and keep looking until you find the right washdown scale, for your specific needs.