Spray Dry Nozzle Safety Standards Compliance

Your stronger engineered choice


Since the early 1970’s, high volume powder production has seen the emergence of nozzle type driers as a major developing trend, resulting in steadily increasing operating pressures to achieve the volumes and consistencies required. This placed enormous demand upon pre-existing nozzle hardware designs, which over this time, had essentially remained unchanged. Today, it is not readily shown that this hardware is operable without significant risk and within accepted safety factors now dictated by modern industry.

Spray Nozzle Engineering has studied many types of drier nozzle hardware in use today. The initial findings of this study were that a generic form of nozzle design has been in common use for some considerable time, from a number of different sources, with most utilising radial seals and very similar hardware geometry. It was also determined through analysis in this study, that a large proportion of such equipment reviewed may operate far in excess of industry accepted stress and pressure limits due to this observed generic geometry and radial seal arrangements. Further, that much of this hardware exists in a worn or old and fatigued condition, which alone, poses a high risk of failure.

Click&Dry™ was developed to function within a range of operational safety factors which far exceed that of current competitive equipment in the field, with unique high pressure axial seals, as well as a design that resists the normal types of observed wear characteristics of older style nozzles in service.

Industries working with pressure systems and vessels, typically stipulate a safety factor of 2-2.5 times based upon the yield stress of the material in use. If operating at a safety factor below 2, a thorough understanding of your fatigue cycles and the potential failure risk is critical. Operating at safety factors approaching 1 or below, ensures failure is imminent based upon known engineering protocol and the properties of typical materials used. This is why Click&Dry™ components are designed around important pressure related standards such as ASME B31.3. These standards are dedicated to safe operation of pressure systems and provide safety margins that exceed those in current use based upon the yield stress and other important factors.

World Wide Sealing standards all dictate the use of backup rings in the typical radial seal arrangements found in most common drier nozzles. Widely adopted global standards typically call for pressure limits of around 100barG without backup rings. One exception is JIS B2406 seal standard which still limits the working pressure without backup rings to only 255barG, this only being achievable with enormously tight radial gap and costly higher duro-rated O-rings. It is clear most modern driers operate far in excess of these pressures and as such require a more reliable and compliant sealing option. Click&Dry™ axial seal arrangement allows for greater operating pressures with no need for expensive backup rings and high duro-seals. This is good news for drier operators in managing operating costs of daily seal replacement.

It can be seen from the review summary below, that many common older spray components in use today operate at pressures far exceeding their yield stress, with a risk of failure, being extremely high. Operating this older equipment at this level is not recommended. This review chart provides the customer with a range of notional safety factors to help them identify the level of operational risk they currently choose to adopt.

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