How To Choose A Suitable WIP Or CIP Sieve Machine? - Senieer

Leakage of highly active drugs will seriously endanger the safety of operators – therefore, as more and more highly active compounds are approved as new drugs, pharmaceutical companies have more and more requirements for the closed production of tablet drugs . Drugs of OEB 3 level (OEL<100 µg/m3) need to be evaluated during the production process whether high-containment production is required, while drugs of OEB 4 (OEL<10 µg/m3) and OEB 5 (OEL<1 µg/m3) In the production process, highly airtight production equipment and technology must be applied. In this regard, this paper introduces the types of tablet sieves, analyzes the problems that should be considered when selecting the type of tablet sieves in the closed tablet pressing process, and compares the respective advantages of WIP sieves and CIP sieves.

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Sieve machines can be divided into non-dust-tight type, dust-tight type, WIP type and CIP type, etc. Of these, non-dust-proof dust collectors are the most common type, but these sifters are not suitable for toxic or highly reactive formulations as they allow dust to escape during operation, especially if there is not enough air for dust collection in the case of. In addition, non-dust-tight machines also need to be disassembled and cleaned, which will expose operators or cleaning personnel to dust in the air.

Dust-proof sieves have positive connections to both upstream and downstream equipment and are fitted with gaskets and seals to prevent dust migration during operation. But like non-dust-tight sieves, they also need to be disassembled for cleaning and are not suitable for hazardous or highly reactive formulations. Therefore, to protect operators and cleaning personnel in hazardous applications, a wash-in-place (WIP) or clean-in-place (CIP) sieve machine must be used.

WIP sieves are dust and water resistant, providing an effective level of containment during operation. WIP machines allow water or water and detergent to be introduced into the machine and all areas within the machine will be fully wetted so no disassembly is required; the water will flush the entire interior of the machine, preventing dry powder exposure and removing most powder from the machine. This allows the operator or cleaning crew to safely disassemble the machine for final manual cleaning and drying without the risk of dust.

Like WIP sieves, CIP machines are dust and watertight and provide an effective level of containment during operation, but they require the use of effective cleaning procedures to verify that no material remains in the machine after cleaning. CIP machines can be completely cleaned and dried without disassembly. They require no human intervention, allowing the line to run on another product or batch as soon as the CIP machine has finished cleaning and drying.

Part 1 Factors To Consider When Choosing A WIP Or CIP Sieve

While WIP and CIP sieves cost more than dust-tight and non-dust-tight sieves, the additional cost of these two types of machines is usually a fraction of the cost of hermetic tablet presses and peripheral equipment. Since dust collectors can remove harmful dust from tablets, it is important to choose a suitable tablet sieving machine. The tablet sieve is also part of the closed system, and the tablet press, sieve and closed tank must work together seamlessly.

In order to adapt the sieve machine to actual production and needs, users need to customize its functions and operations. To do this, a User Requirements Specification (URS) should be developed to document all system expectations and approved by all user groups. Before purchasing a WIP or CIP sieve machine, users should consider the following questions:

What Is Our Normal Production Requirement?

How dangerous are our products? What is the Occupational Exposure Limit (OEL) range? What is the time-weighted average tolerable concentration for occupational exposure limits? Does the material require manual handling?

• Is the special sieve machine easy to assemble and disassemble?

• What layout do we need to handle upstream and downstream processes?

• How will we control the flow of water? Are there restrictions on water use?

• How will we manage the make-up air for dust collection?

• How will we handle equipment failure?

• Whether metal detection is required in the production process?

• Do we need a diverter for multiple tanks?

Normal Production Requirements

Determine the demand for capacity and dust removal efficiency, as well as the requirements for the relevant physical parameters of conventional sieving machines. This includes tablet size and shape, press production speed, press exit height, and barrel height.

Dangerous Product

Occupational exposure hazards for products and powders are classified into 5 levels, OEB 1 to 5, where 1 is the highest level for which exposure is permitted and 5 is the lowest level. The measurement unit of OEL level is μg/m3, ～ μg/m3 is OEB 1, and OEL<1 μg/m3 is OEB 5.

At this point, the WIP or CIP machine leak-tightness should be verified using the Standardized Measurement of Particle Concentration in Equipment (SMEPAC) guidelines. SMEPAC is a guideline sponsored by the International Society for Pharmaceutical Engineering (ISPE), which gives performance testing standards that allow pharmaceutical companies to accurately compare machines.

Assembly And Disassembly

Evaluate the ease of assembly and disassembly of the desired sieve. For example, are special tools and procedures required for disassembly and reassembly?

Layout

Consider the desired layout and determine how the machine will interface with upstream and downstream equipment, and how connections will be made and broken when the machine is dismantled and cleaned. These connections may be split butterfly valves, other closed valves, or continuous liner systems, each of which requires vertical space that must be accounted for in the layout. The tablet press connection, the discharge chute from the tablet press to the tablet sieve, the connection to the tablet sieve, metal detectors and tanks must all be WIP or CIP capable to ensure no dust escapes from the system.

Water Control And Use

Determine the discharge of water during a WIP or CIP process. Water usage is also a consideration, as pharmaceutical companies must collect some hazardous materials and dispose of them in hazardous waste collection facilities. By minimizing water usage, disposal costs can be kept low over the life of the machine. If off-line cleaning is to be performed, it must be determined how to disconnect the sieving machine from upstream and downstream equipment in a closed manner.

Dust Collection

Ensuring continuous dedusting in the sieve, with no fluctuations in flow and vacuum pressure throughout the batch, is necessary to maintain proper system performance. It should be determined in advance how the make-up air for dust collection will enter the sifter and what will happen if it fails. For example, if the sieve machine is positive pressure, will the positive pressure cause dust to be blown into the clean room?

Since the tablet press, sieve and hopper are all connected in series, there may be a separate dust collection system for the tablet press and sieve. Faced with this situation, the dust collection system must be properly balanced. If they are not balanced, the dust collection airflow of the tablet press is stronger than the dust collection airflow of the sieve machine, then the tablets may be pulled back into the tablet press. In addition, the dust airflow can cause problems for the tablets to flow out of the sieve machine and into the bin.

Equipment Failure

Determine how to handle all possible equipment failures. What is the company’s contingency plan in the event of a breakdown? What if the machine has to be opened during production? Does the company have a plan to safely open the machinery in an emergency using personal protective equipment?

Metal Detection

Determine the need for metal detection. Determine how to introduce the test piece of the metal detector in a closed manner. How to remove the test piece in a closed manner after it has passed through the metal detector? How to remove rejected pills from a metal detector in a closed fashion?

Shunt

Determine if a diverter is required at the discharge of the sieve machine. The splitter allows the use of multiple tanks to avoid shutting down the tablet press and screener when changing tanks.

Part 2 Comparison Between WIP Sieve And CIP Sieve

The main problem hindering automatic cleaning of sieve machines is that sieve machines have many nooks and crannies, and it is difficult for an automated system to clean them in a reviewable and fully verifiable manner. Therefore, WIP sieves are more common than CIP sieves.

In theory, CIP sieves appear to save cleaning time, but in reality, verifying the consistency of cleaning for each product is time-consuming, requiring electronic storage of the CIP recipe in the machine’s control system. Also, in addition to the cleaning process, the drying process needs to be validated to ensure that the sieve machine is completely dry before production starts again.

Part 3 Summary

The pharmaceutical industry is a highly regulated industry. When a pharmaceutical company produces or changes any product, it must report its production process to the State Drug Administration. This is an extremely tedious and complicated process, which will not only affect production efficiency, but also increase unnecessary losses for the enterprise. Therefore, when pharmaceutical companies choose WIP and CIP sieve machines, they need to fully consider how to make upstream and downstream equipment better compatible with each other, and do a lot of thinking and coordination to ensure their effectiveness. An experienced supplier of WIP and CIP sieve machines can help customers deploy a robust system that provides a high level of effective, trouble-free containment protection for their specific application.

Quick, name the most widely used and cost-effective scientific instrument in your laboratory. Some possibilities come to mind, but our argument is for the ordinary test sieve. By a wide margin, there is no more simple, efficient, or cost-effective way to profile particle dimensions for an extensive range of materials than test sieving.

Sophisticated instruments that take more precise measurements have their place in particle analysis. However, the benefits gained can’t always offset the effort and costs when basic particle sizing and gradations are the focus. These instruments can also confuse traditional interpretations of accumulated historical data if the results do not correlate with mesh sieve testing.

What is the Purpose of Test Sieves?

Sieving is an ancient science based on simple principles deeply rooted in materials testing laboratories as a standard method for measuring particle size. There has always been a question of the absolute accuracy of particle sizing by sieving since the process assumes each particle to be a perfect sphere.

Why Sieving?

It has been practiced for so long on so many different materials that variations in shape for things like construction materials, chemicals, food, pharmaceutical granular material, powders, and many other products are accepted. Each of these disciplines have developed published test methods for their materials. ASTM also publishes their own. The Manual 32 - Test Sieving Methods, is ASTM's comprehensive guide for test sieving methods and analysis procedures.

ASTM E11 and ISO -1 standards list specifications for woven wire sieves. Particles from 150mm (6in) to 5µm (0.in) can be sieved effectively using appropriate test methods.

The Standard Sieve

So, while test sieves are quite simple, they are still scientific instruments that should be selected, used, and maintained carefully. Let’s take a closer look at the mesh sieve itself, sieve construction, materials, and design options.

Selecting the Type of Sieve to Fit Your Needs:

Selecting the Separation Media

The separation medium for most sieves is metal or synthetic woven wire mesh. Perforated metal plates are another separation medium, as is electroformed mesh, a flat metallic sheet with precision openings.

For conventional ASTM/ISO test sieves with woven-wire mesh, the range of opening sizes is 125mm to 20µm (5.0in to No.635). It is left to industry-standard test methods, or sometimes the operator, to determine which opening sizes suit a particular sample.

Some test methods dictate the required openings or sieves may be selected to provide useful information on a gradation curve. It is common to use every second or fourth size in the series for an even indication of distribution. An intermediate sieve inserted into the stack can prevent overloading or better define a range of sizes.

Different Types of Sieve Media

Woven-wire mesh is fabricated on large industrial looms in various weave patterns using metal wire. The wire mesh is cut to size and mounted on frames by soldering or with high-strength epoxy adhesives. Proper tensioning ensures uniform openings and prevents finer wire cloth meshes from stretching and sagging during use, increasing the service life of the sieve.

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• Brass wire mesh has been favored in the past for sieves because of its malleability and formerly lower cost. It is still sometimes desirable for certain hazardous materials because of their resistance to sparking. The brass mesh is available in sizes from 2.36mm to 45µm (No. 8 to No. 325).
• Stainless steel mesh is much more durable, less likely to contaminate sensitive materials during processing, and maintains its specified openings better. These days, it also features lower cost than brass, and modern tooling makes it easier to weave, form, and mount. Stainless steel mesh is available in the full range of ASTM/ISO sizes from 125mm to 20µm (5.0in to No.635).

Non-metallic mesh woven from polyester or nylon filament is available for non-metallic sieves for unique applications or as a disposable cloth for use in two-part sieve frames. This synthetic mesh is useful for applications where the metal mesh is not permissible or may become contaminated. Opening sizes are equivalent to many ASTM/ISO sizes, but synthetic cloth does not meet E11 or -1 requirements for the material type or wire diameter.

Perforated plate is a precision-punched steel plate meeting requirements of ASTM E323. Perforated plate is often used for the sieve analysis of coal (ASTM D), or ores, coke, wood chips, and other special materials. Perforated plate openings range from 3.18 to 100mm (1/8 to 4.0in).

Electroformed mesh opening sizes are square, highly accurate, and very consistent. Tolerances are held to ±1 to 2µm for openings from 150µm to 5µm. This sieving media is expensive, and the fine mesh can be fragile, but it is the optimum choice for applications where precise sizing of fine materials is critical. Nickel used to manufacture electroformed mesh is electrodeposited on a flat stainless steel grid surface. ASTM E161 and ISO -3 specifications list tolerances for these sieves, and they are individually measured and supplied with documentation of compliance.

Selecting the Frame

Just as opening sizes must be selected based on material size, consider the frame type when choosing sieves.

Sieve frames provide a stable platform for proper mounting and tensioning of the sieve mesh and confine the sample material during agitation. Round test sieves include a skirt that enables nesting with other sieves, forming a multi-sieve stack for use in a sieve shaker.

Frames for conventional round test sieves are available in several configurations, and selecting the right one makes a difference for each application. A previous blog post goes into detail about unique frames like Screen trays for Testing Screens, wet-wash sieves, and other sieves for less common applications.

Frame diameter is a crucial step in matching the size of the sieve to the sample volume. Large samples contained within a frame that is too small result in poor separations when particles do not find sieve openings. Size fractions are not entirely separated. A rule of thumb for matching frame diameter to sample volume is that no more than one or two layers of material should remain on a sieve after separation is complete.

Selecting a large sieve allows a larger, more representative sample to be used and promotes better division of fractions. Conversely, smaller sieve frames offer better control over small specimens of fine powders and are easier to clean for the complete recovery of particles. Some test methods recommend test sieves to have a minimum of five full openings, so any sieve has limitations on the upper size of mesh openings.

The chart below lists frame dimensions for ASTM E11 and ISO test sieves.

Frame height options allow you to maximize testing efficiency when separating multiple fractions on a sieve shaker. Half-height sieves allow a greater number of sieves in a stack in the same vertical space. Bear in mind that during agitation, each particle must have enough room to be lifted off the mesh surface, reorient, then land back on the mesh in a different position, so coarse particles will still require a full-height sieve.

Frame material selection is most often a practical matter of price, long-term durability, and requirements of the application.

• Stainless steel is the optimum choice for most applications for its lower cost, long service life, low rate of sample contamination, and resistance to corrosion.
• Brass has become more expensive recently but is a traditional choice and can still be useful for testing certain materials where sparking could be a concern.
• Combination Frames feature Stainless steel mesh with a brass frame hoop and a stainless-steel skirt for added durability.
• Acrylic frames have certain advantages for smaller sieves. The material is easily machined for a precise nesting fit and allows visual monitoring of the sample during agitation. High-strength adhesives securely anchor the sieve mesh to the frame.

Backing cloth is an option designed to increase the useful life of the primary sieve and offset the effects of frequent use and overloading. The coarser, stronger No. 30 (600µm) wire mesh is factory-installed under the finer primary mesh of No. 70 (212µm) and finer test sieves as reinforcement, especially for wet-wash sieves.

As an industry leader for particle sizing equipment, Gilson is a major resource for useful information on sieves and sieving. Below are links to a selection of videos and previous blogs from our archives that we think are most useful to this series. Please visit our video or blog pages for complete listings.

Helpful Sieve Analysis Resources:

Gilson Videos:

Gilson Test Sieves

ASTM C136 Sieving Test Method

Cumulative vs. Fractional Sieving

Wet-Wash Sieves

Wet-Wash Sieving Methods

Acrylic Frame Test Sieves

Sieve Cleaning

New Sieve Verification

Re-Verification of Used Sieves

Master-Matched Sieve Services

Gilson Sieve Shakers

Tapping Sieve Shakers

8in/12in Sieve Shakers

3in Vibratory Sieve Shaker

3in GilSonic AutoSiever

We hope this blog post has helped you understand the form and function of test sieves. Please contact us with questions about your applications.

Testing Resources

Standard Test Methods, Specifications, and Practices

Individual test methods and specifications referenced in our product descriptions, blog articles, and videos are available for review or purchase from the professional organizations noted.

Contact us to discuss your requirements of powder sieving machine price. Our experienced sales team can help you identify the options that best suit your needs.