HP4750 Stirred Cell
The Sterlitech HP4750 stirred cell is a high-pressure stirred cell that is both chemically resistant and features a low hold-up volume (1 ml). This particular brand of stirred cell is able to perform a wide variety of membrane separations.
HP4750 Stirred Cell Product Benefits:
- Max operating pressure is 1000 psi
- Removable PTFE stir bar
- 316 stainless steel
• Safe Operation: Volatile solutions can be processed safely because the Sterlitech™ HP4750 operates on standard sources of compressed air or inert gases (nitrogen, argon, etc.). This provides the user with a variable, safe and consistent supply of pressure to effect membrane separations.
• High-Pressure Operation: Solutions with high levels of dissolved solids and high osmotic pressure can be separated with the Sterlitech™ HP4750. The cell is designed for safe operation to 1000 psig (69 bar).
• Removable Stir Bar: Concentration polarization at the membrane surface is minimized by a PTFE-coated magnetic stir bar mechanism. The stir bar can be driven by any standard stirring plate.
• Accepts Standard Membrane Discs: Sterlitech™ HP4750 Stirred Cell accommodates any 47 to 50 mm diameter membrane disc.
• Chemically Resistant Materials of Construction: 316L stainless steel construction makes the Sterlitech™ HP4750 resistant to most chemical degradation. Buna-N gaskets and O-rings are provided as standard with other optional materials available to meet operating requirements.
• Unique Design: The cell top can easily be removed to fill the vessel with up to 300 mL of solution. The cell bottom is removable for quick membrane change-out. The top and bottom are secured to the vessel with mechanical couplings. This unique design enables low hold-up volume, down to as low as 1 mL, so valuable solutions are not wasted.
|Membrane Size||1.93 in dia. nominal (49 mm)||1.93 in dia. nominal (49 mm)|
|Active Membrane Area||2.26 in2 (14.6 cm2)||2.26 in2 (14.6 cm2)|
|Processing Volume||Up to 300 mL||Up to 300 mL|
|Hold-Up Volume||1 mL||1 mL|
|1000 psig (69 bar) w/high-pressure clamps||2500 psig (172 bar)|
|250 °F (121 °C) at 800 psig (55 bar)||400 °F (205 °C) at 2000 psig (138 bar)|
|pH Range||Membrane Dependent||Membrane Dependent|
|Connections||Permeate Outlet: ⅛ in dia. 316L SS tubing;
Pressure Inlet: ¼ in FNPT
|Permeate Outlet: ⅛ in dia. 316L SS tubing;
Pressure Inlet: ¼ in FNPT
|316L Stainless Steel||316L Stainless Steel|
|Buna-N, others available as options||Viton or PTFE|
|Buna-N, others available as options||Viton or PTFE|
|2.0 in (5.1 cm)||2.75 in (7.0 cm)|
|7.8 in (19.9 cm)||10 in (22.4 cm)|
|5.7 in (14.6 cm) w/high-pressure couplings||NA|
Principles of Operation (image will open in new window)
HP 4750 Stirred Cell
I have a membrane sample that is too large to fit in my stirred cell. Can I cut it to fit?
Yes, you may cut the membrane to fit in your stirred cell. You can use the support disk from the stirred cell as a template.
What type of stir plate do you recommend for use with the stirred cells?
Any conventional magnetic stir plate will work. Sterlitech recommend the Scilogex MS7-Pro,
How do I release the pressure on a stirred cell?
The user must completely release the pressure before opening a stirred cell. The HP4750 and HP4750X stirred cells do not have integrated pressure relief valves, but Sterlitech does offer an accessory bleed valve for purchase which can be attached to the regulator's outlet to the high pressure hose upstream of the stirred cell. https://www.sterlitech.com/pressure-relief-bleed-valve-2500-psig-1155893.html. The bleed valve can be slowly opened to release pressure when necessary for sample removal or refilling.
The polymeric stirred cells have integrated pressure relief valves. These valves can simply be opened to release the pressure when necessary.
Can I use the alumina oxide (AO) membrane disk filters in the stirred cells?
Yes, you can use the AO (https://www.sterlitech.com/alumina-oxide-membranes.html) membrane disk filters in the stirred cells. These disk filters are very brittle and must be handled with an abundance of care to avoid breakage. Use membrane tweezers to carefully place the disk filter on the surface of the support disk and then install the support disk in the stirred cell body.
Can I cut a membrane for use in the HP4750?
Q. Can I cut a membrane for use in the HP4750?
A. Yes, use the metal membrane support as a guide for cutting a disc.
Can I use microfiltration membrane disk filters in the stirred cells?
Yes, you can use almost all microfiltration membrane disk filters in the stirred cells. The only exception are the ceramic membrane disk filters; these are too thick to fit in the stirred cells.
What do I need to operate a stirred cell?
You can find a diagram for a typical stirred cell system at https://www.sterlitech.com/media/wysiwyg/Manual/HP4750_Flow_Diagram.png. In addition to the stirred cell itself, the user will require a pressure source consisting of a regulated supply of compressed inert gas or air, a bleed valve for releasing the air pressure, an appropriately sized magnetic stirring plate, and a permeate collection vessel (e.g. flask or beaker) to collect the filtrate.
Do I need to precondition the membrane disk used in a stirred cell?
Yes, for flat sheet membranes that will be used with water or aqueous solutions, we recommend that you pre-condition the membranes prior to conducting your separation experiments. Pre-conditioning helps ensure that the membranes perform as expected. Also, pre-conditioning removes preservatives and other residuals from the membranes.
To pre-condition the membrane disk, install it in the stirred cell and then fill the stirred cell with purified deionized water. Initiate operation of the stirred cell at the pressure and temperature expected for the separation experiments. Allow the cell to operate until the permeate flux has stabilized at an expected value. Then release the pressure, discard any water remaining in the stirred cell, and discard the water from the permeate collection vessel. You may now proceed with your experiments by refilling the cell with the desired feed sample. At no time should the wetted membrane disk be allowed to dry.
Do you have operating manuals for the stirred cells?
Why am I not achieving the membrane manufacturer’s published rejection and/or permeate flux while using my stirred cell?
It is important to note that membrane manufacturer’s specifications for rejection and permeate flux are usually based on testing of large area spiral wound membrane elements operating in crossflow mode using standardized feed streams and pressures. It is normal, and to be expected, that rejection and permeate flux will be different for feed streams and pressures that are not similar to the standardized test conditions. It is also normal, and to be expected, that rejection and permeate flux will have greater variability from published specifications for devices with membrane active areas that are very much smaller than spiral wound elements, such as stirred cells. Some amount of concentration buildup in the feed for stirred cells is inevitable and this may affect rejection and permeate flux.
There are some tactics that can be used to optimize rejection and permeate flow while using stirred cells. First, the membrane should be pre-conditioned using purified deionized water. Please refer to the operating manual for the pre-conditioning procedure. Second, make sure that the stir bar is turning properly and at an appropriate rate. Third, the operating pressure should correspond to the membrane manufacturer’s recommended pressure. Finally, you may want to stop your experiments while there is still some feed liquid remaining in the stirred cell to mitigate effects associated with increasing concentrations.
Can I attached the stirred cell permeate line directly to an HPLC analyzer or other laboratory instruments?
Yes, you may connect the permeate line directly to an instrument. However, it is important to understand that if the membrane fails or is allowed to dry, then the full feed pressure may be applied to the permeate line. If the instrument cannot withstand the feed pressure, then directly connecting the permeate line is not recommended. Alternatively, if the membrane becomes prematurely fouled (due to a high TDS or particulate loading), permeate levels may drop below detection in the HPLC inlet port.
What is the maximum membrane thickness for the stirred cells?
The stirred cells are designed to accept flat sheet membranes with thickness of 350 microns or less.
What is the pore size rating for the porous support disc (SKU 1114910)?
The porous support disk has a nominal pore size of 20µm.
I’m purchasing the high-pressure gas regulator assembly (SKU 1144026) for use outside of the United States. Will I need a conversion kit to attach it to my gas cylinder?
The high pressure gas regulator assembly is supplied with a CGA 580 fitting, common in North America for use with commercial inert gas cylinders. Sterlitech also offers an optional DIN 10 fitting (https://www.sterlitech.com/pressure-regulator-conversion-kit-din-10-assembly-1-4-nptm.html) for use in numerous European countries. If the CGA 580 fitting or DIN 10 fitting are not suitable, please contact your local specialty compressed gas supplier for an appropriate fitting that is compatible with the North American ¼” NPT female threads of the Sterlitech regulator ports.
What is the correct membrane disk diameter for the HP4750 stirred cell?
The HP4750 stirred cell will accept a membrane disk of 47mm to 49mm in diameter.
What are the materials of construction for the HP4750 stirred cell?
The HP4750 stirred cell is composed of 316 stainless steel, but is alos available in Hastelloy C-276 for highly corrosive environments. The magnetic stir bar is PTFE coated to prevent corrosion and to ensure broad chemical compatibility. The standard seals are composed of Buna-N; other seal elastomers are optionally available.
Is there a mechanical stirrer option for the HP4750 stirred cell?
Yes, there is a mechanical stirring option for the HP4750 stirred cell. The mechanical stirrer is available with either a 110V or 230V rated motor. Please note that the shaft adapter of the mechanical stirrer occupies the 1/4” FNPT pressure port in the stirred cell top and has a 1/8” FNPT pressure port.
Why would I use the mechanical stirrer for the HP4750 stirred cell?
The mechanical stirrer (https://www.sterlitech.com/mechanical-stirrer-with-stir-bar-and-shaft-1144035-110.html) is typically used for processing fluids with high viscosities that would stall a magnetic stir bar.
What is the maximum operating pressure for the HP4750 stirred cell?
The maximum operating pressure for the HP4750 stirred cell is 1000psi (69bar) at room temperatures. However, the actual maximum operating pressure may be limited by the membrane being used.
What is the maximum operating temperature for the HP4750 stirred cell?
The maximum operating temperature for the HP4750 stirred cell itself is 250°F (121°C) at ≤800psi (55bar). However, the actual maximum operating temperature may be limited by the seal elastomer or by the membrane being used.
Can I use the 47mm ceramic membrane disk filters in the HP4750 stirred cell?
No, the ceramic membrane disk filters are too thick to fit in the HP4750 stirred cell. Although not recommended by Sterlitech, some users have reported being able to close and operate the HP4750 stirred cell by replacing the support disk with a 47mm ceramic membrane disk filter. However, success was almost always limited to low pressure use and physical damage to the disk filters was very common.
I need to replace the Swagelok compression fittings on my HP4750 stirred cell. What are the thread sizes for the ports?
The pressure port in the top of the HP4750 stirred cell has 1/4” NPT female threads. If the mechanical stirrer is being used, the pressure port in the shaft adapter has 1/8” NPT female threads.
The permeate port in the body of the HP4750 stirred cell has 1/8” NPT female threads.
If you would prefer to source the Swagelok fittings from Sterlitech, please contact us for pricing and availability.
Can I use a membrane disk smaller than 47mm in the HP4750 stirred cell?
Typically, membrane disks smaller than 47mm in diameter cannot be used in the HP4750 stirred cell. However, some users have been able to accommodate smaller disks by blanking the unoccupied area with an appropriately sized annular flat gasket. Please contact us if you desire to use smaller disks in the HP4750 as we may be able to provide some assistance.