FFKM Inner and Outer O-Rings for Sepa CF Cell

FFKM is highly solvent-resistant and a comparable alternative to Chemraz™ O-rings.
  • SKU
    1220130
  • Pack Size
    1
$822.04
+ -

Sterlitech offers a number of SEPA CF Cell optional parts and accessories. Options include:

  • SEPA CF Cell O-ring kits
  • SEPA CF Cell tubing
  • SEPA CF Cell feed spacers
  • SEPA CF Cell permeate carrier membrane
  • SEPA CF Cell shims
  • SEPA CF Cell concentrate control valve

See the Applications tab for detailed descriptions of accessories.

Click hereto go to SEPA CF Cell

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Item No. Description Size Quantity
1143205 SEPA CF Viton O-Ring Kit Accessory N/A 1
1232558

SEPA CF Assortment Feed Spacers Pack

Diamond Spacer Type:

(a) 17 mil (0.432 mm);

(b) 34 mil (0.864 mm);

(c) 47 mil (1.194 mm);

(d) 65 mil (1.651 mm)

Parallel Spacer Type:

(a) 47 mil (1.194 mm)

145x97 mm   5
1149418 SEPA CF Concentrate Control Valve, High Pressure Accessory   N/A 1
1231104

SEPA CF Shims (Stainless Steel)

(a) 1 of 2 mil (0.051 mm);

(b) 1 of 3 mil (0.076 mm)

(c) 1 of 4 mil (0.102 mm);

(d) 1 of 5 mil (0.127 mm);

(e) 1 of 10 mil (0.254 mm);

(f) 1 of 15 mil (0.381 mm)

145x97 mm 12
1142819 SEPA CF High Foulant Spacer,
65 Mil (1.651 mm)
145x97 mm 5
1142818 SEPA CF Low Foulant Spacer,
34 Mil (0.864 mm)
145x97 mm 5
1143763 SEPA CF Medium Foulant Spacer,
47 Mil (1.194 mm)
145x97 mm 5
1142817 SEPA CF Permeate
Carrier Membrane
145x97 mm 5
Sepa Hose High Pressure Braided Hose with End Fittings 48" 1

Q. What is the difference between Sepa CF and Sterlitech HP4750?

A. The Sterlitech HP4750 is an enclosed batch system (limited to 300ml) with direct filtration under pressure. There is a stir bar mixing the solution and pressures up to 1000 psi may be applied.

The Sepa CF is a crossflow system that allows continuous sampling and testing under different pressure and flow rate parameters depending on the pump and fluid.

Q. Does the feed spacer penetrate the membrane?

A. The mesh spacer usually leaves an imprint on the membrane which is not a problem - unless too thick of a mesh is used - then it could damage the membrane.

Q. How do I calculate Reynolds number based on the feed cross-flow velocities for the various feed spacers?

A. The Sepa CF cell for use with high fouling spacer has a flow area width and height of 3.7 inches by 0.068 inches. Once a spacer material is placed in the channel the actual flow channel cross section is significantly reduced. We have not calculated that. We typically operate the cell and estimate the Reynolds number at the transition from laminar to turbulent flow by monitoring the increase in pressure drop as the crossflow is increased.

Another usage implementation which we have used is the placement of a rubber gasket in the flow channel. A specifically sized flow channel can be cut out of the gasket to define a flow channel of the desired cross section.

We actually have done more study of the CF cell for use with standard spacer (3.7 in. by 0.034 in. cell cross-section). We evaluated that cell for various cross flow velocities at various feed flow rates.

Q. How do I distinguish between the low foulant (34ml) feed spacer and the high foulant (68ml) feed spacer when I hold them in my hands?

A. The low foulant has smaller squares and bends slightly easier.  It feels lighter.  It is not stiff like the medium foulant.  The high foulant spacer has corragated ridges in it like cardboard.  No holes.

Q. Is the low foulant spacer the same as the permeate carrier?

A. No, the low foulant spacer is under the membrane and the permeate carrier is on top. The membrane is sandwiched between the spacer and permeate carrier.

Q. In the instruction manual of the Sepa CF, tubular and mesh spacers are mentioned. Can I conclude that the tubular is the low foulant and the mesh is the high foulant?

A. The mesh spacer is a low (34 ml) and also the medium spacer (68 ml).

The tubular spacer is for high foulants (68 ml) and looks like corregated cardboard.

Q. Could the filter cloth of industrial filters be used in the Sepa filtrations units, after cutting it to proper size?

A. The Sepa CF can potentially work for any media that can be fitted into the chamber.

One thing that could be an issue for some types of filter media is whether or not a sufficient seal is made between the O-ring and the media. For membranes, this is not a problem because membranes have a relatively smooth surface, which affords good mechanical seal when pressed together. A large fiber woven material, for example, may need to be modified or filled with some type of potting compound to level the surface in order to get a non-bypass seal.

Q. Can I use the Sepa CF membrane cell without spacers?

A. Using the cell without any spacers will usually cause wrinkles in the membrane. The depth of the cell is made to accommodate the spacer that will fit in it (34 or 68 ml).

Q. How can I set the maximum flow from my Sepa CF?

A. Most separations and flux through membranes are controlled by the nature of the fluid. For salt rejecting membranes, such as RO and NF, the dominant variables are operating pressure and osmotic pressure (a solute concentration-dependent property which reduces net operating pressure with increased solute concentrate).

The pumping rate or fluid velocity across the membrane is another important operating parameter; an increased velocity results in improved mixing of the layer of feed solution directly above the membrane. The removal of fluid through the membrane results in accumulation of rejected solutes in this layer, often referred to as the boundary layer. The boundary layer can contribute a significant resistance to flux through the membrane as levels of solutes increase.

The accumulation of solutes in the boundary layer is often the most limiting factor in membrane flux, particularily for the larger pored membranes (NF, UF, and MF). There generally is a finite operating pressure, above which provides little or no flux benefit.

An increase in the feed solution velocity across the membrane, combined with turbulence promoting mesh spacers, can provide the optimal combination of operating conditions. Consideration of energy imput and mechanical load due to pressure drop across the membrane are practical limitations for operation of membrane systems.

To find maximum flux, we set the feed flow to a maximum practical rate, and increase the operating pressure incrementally while monitoring flux (filtrate) output. A given operating pressure will yield a certain maximum output for a specific feed solution.

If the feed solution becomes more concentrated, such as occurs for a dewatering objective, the optimal operating pressure will typically decrease as the solute concentration increases (the exception to this would be if the osmotic pressure increase due to concentration becomes significant). The input energy may be better applied to higher cross flow velocity if practical.

A practical method may include operation at a pressure setting slightly lower than the maximum initial rate determined. This is produce highest flow, best flux, and least amount of build up on membrane.

Q. What is the definition of GFD?

A. GFD = Gallons Per Square Foot of Membrane Per Day

Q. Will there be a difference in flow rate on the Sepa CF if it is run continuously or in intervals?

A. If permeate flow rate verses time for both membranes are plotted will there be a difference?

There should be a difference in the plots - at least initially. There is typically a "conditioning" affect that occurs as the result of mechanical compression, some of this affect is reversible to an observable amount if operation is intermittent.

This will yield a "zigzag" appearance to a graph of operation vs. time or cumulative hours of operation. The trend with the intermittent operation would be to gradually approach a standard.

Q. What fluid do I use in my Hydraulic hand pump for my Sepa CF?

A. The unit uses standard grade hydraulic oil. It has a reservoir located under the handle at the furthest end with a cap on the reservoir.

The amount of oil used will depend on the length of line, hose.

The recommended oil has a viscosity rating at 100°F.

SUS rating 150-165

SAE 10 wt oil Hydraulic oil (do not use other types of oils)

General purpose

150-165 thickness

Rating 210°F 42-45

Q. What is the proper way to store the membranes for the Sepa CF after they have been used?

A. We recommend that the membranes for the Sepa CF be kept wet once used. Either keep the water fresh (change every couple of days), or add ~0.5 sodium metabisulfite (preferred) to keep bacteria from growing.

Q: What are the torque settings for the CF042 and Sepa CF Cells?

A: Best practices for plumbing of polymer (Acrylic, Delrin, and PTFE cells) CF042 cells, include the use of PTFE tape properly installed on 1/4npt threaded coupling, and the use of a light coat of PTFE-based pipe thread sealant, then the coupling needs to be seated in the base of the cell using the following torque settings:

  • Delrin- 60 inch pounds
  • Acrylic -70 inch pounds
  • PTFE -15 inch pounds OR until the fitting "shoulders" out on the base of the CF042 cell*

*extreme caution should be used to assure that the fitting is not started incorrectly (cross-threaded).  In normal installation, the fitting should easily turn in several turns without tooling (by "hand") before using the torque wrench.