Cross and Tangential Flow Test Cells
Cross and Tangential Flow Test Cells are bench-scale cross/tangential flow membrane test cells used in pressure driven applications. Sterlitech offers test cells that are designed for small scale crossflow filtration testing using polymeric flat sheet membranes in a wide range of RO, NF, UF and MF. Sterlitech also offers a bench-scale test cell for tubular ceramic membranes: Valisette ceramic test cells. Sterlitech Cross/Tangential Flow Cells can be incorporated into any Benchtop or Skid Mounted System.
In general, the feed solution is circulated tangentially to the membrane filter in the crossflow/tangential flow membrane test cells. Molecules or materials which are smaller than the membrane's molecular weight cut-off (MWCO) or porosity pass through the membrane as permeate and the remainder is retained on the feed side of the membrane as retentate.
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Frequently Asked Questions
Q: What is the recommended flow rate for the CF cells?
Please refer to the following diagram to examine recommended feed flow rates for the crossflow cell you are working with.
Q: Why is the flat sheet membrane I'm using measuring a flux value less than the published flux value?
Flow characteristics for a spiral element and flat sheet membrane are significantly different and are really only comparable on a qualitative basis. Variability in the membrane manufacturing process, differences in water composition, test procedures, and test equipment, used in a factory, laboratory, or elsewhere, will impact water flux results.
Q: What are the available materials of construction for the Sterlitech crossflow test cells?
The Sterlitech bench-scale crossflow test cells are available in a variety of materials to suit most applications:
- Stainless Steel
- PTFE
- HastelloyTM
- Delrin (natural acetal copolymer)
- Acrylic
Addtionally, there are a variety of available o-ring seals including Buna-N, EPDM, Viton, FEP encapsulated Viton, and FFKM (Markez).
Q: How do I install/remove permeate fittings or other plastic NPT fittings?
Sterlitech recommends to install all plastic fittings by hand using PTFE tape. If a plastic NPT or compression fitting starts to leak during operational testing, tighten the fitting carefully until the leaking stops. Excessive tightening may break the fitting or damage other components.
If the fittings is broken and stuck in the cell top, use a spiral flute extractor bit or similar tool to release the portion of the fitting in the cell top. If the cell top becomes cracked from removal efforts, a replacement can be purchased.