Below you will find a list of frequently asked questions.


How can I order Optimize Technologies products?

Optimize Technologies products can be ordered through any authorized dealer - whether in the United States, or worldwide - by phone (800-669-9015 or 503-557-9994), fax (503-557-9995), and online. If you do not have an Optimize Technologies dealer in your region, please contact us to either order directly from our company, or for a dealer recommendation.


How late can I place an order for same-day shipping?

Orders placed directly with Optimize Technologies before 12pm PST on a business day will normally ship that same day, if the items ordered are in stock (pending credit approval).


What forms of payment do you accept?

We offer NET30 terms to approved customers with accounts in good standing. We also accept Mastercard, Visa, American Express, and PayPal.


What is the Optimize Technologies return policy?

At Optimize Technologies, our products are fully guaranteed to meet or exceed original equipment specifications, and to meet your own demanding expectations. Quite simply, your satisfaction is guaranteed. If you are unhappy with any analytical products you receive from us, please contact us, or the authorized distributor from whom you purchased the item.

A Return Materials Authorization (RMA) number must be obtained before any product can be returned to us. The RMA number allows us to properly identify returned goods, and to resolve problems quickly and efficiently. Optimize Technologies is not responsible or liable for goods returned without prior authorization. Most returns and exchanges are accepted up to 12 months after purchase. Lamps, however, are accepted for only 30 days. Please contact an Optimize Technologies representative for more information.

OPTI-MAX® Check Valves

How do I know what check valve replacement cartridge I should order? 

The middle two and very last digit found in the part number of your check valve housing directly correspond to the check valve replacement cartridge you are looking for.

The first middle digit – This number signifies the size of the replacement check valve cartridge.

  • 10-3x-02004: 1/32”
  • 10-4x-02004: 1/16”
  • 10-5x-02004: 1/8”
  • 10-6x-02005: 3/16”
  • 10-7x-02004: 1/16” (UHPLC pressures)
  • 10-8x-02004: 1/16” (Double ball UHPLC pressures)

The second middle digit – This number signifies the type of material the replacement body and ball and seat are created from.

Second Middle Digit

Cartridge Material

Ball & Seat Material


Stainless Steel



Stainless Steel








The last digit –

  • 10-xx-02004: All check valve replacement cartridges ending in 02004 are interchangeable between all OPTI-MAX housings (except xx-6x-xxxxx)
  • 10-xx-02005: Check valve replacement cartridges ending in 02005 require Extended Flow housings (xx-6x-xxxxx)


Are your check valves self-priming? 

Question:  I read somewhere about some cartridge check valves that are "self-priming." Is this true for OPTI-MAX® check valves? 

Answer:  We've seen check valve manufacturers claim that their check valves are "self-priming". We do not understand this to be possible. 

The check valves found in almost all LC systems are passive flow restriction devices. The ball opens and closes in response to pressure gradients - differences between the pressure before and after the check valve. When the pressure at the check valve inlet exceeds that at the outlet, liquid flows through. When the pressure is higher at the outlet, the check valve closes.

So, how do "self-priming" check valves entice the mobile phase to flow up the inlet tubing and into the pump head? Nothing. Or rather, nothing different than other check valves.

In our experience, there is only one thing that will cause mobile phase to flow into the pump head: hydrostatic pressure. It could be positive (generated by elevating the solvent reservoir or applying head pressure within a sealed solvent reservoir using a sparging gas) or negative (a vacuum generated by a priming syringe, or by the piston of your LC pump). All a check valve has to do to help is to stay out of the way! You certainly want a check valve that offers minimal resistance to flow in the positive direction (and maximal resistance any other time), but to say that a passive check valve is playing some active role in the pump priming process is misleading.

Manufacturers say that with their "self-priming" check valves, pump priming becomes a simple matter of dunking your solvent line in the reservoir, turning your dry pump on at 5mL/minute, and putting your feet up while the pump does all the work. Do not follow this advice! You should avoid turning on your LC with a dry pump head. A dry piston dragging back and forth through a dry piston seal will bring liquid up into the head, but it will also cause increased seal and piston wear causing you to replace seals much earlier than you'd like. Wetting the seal and piston with solvent as quickly as possible will help both components last longer. If you can get liquid to the head simply by opening a purge valve and elevating the mobile phase, great! If not, use a priming syringe to get liquid to the head before you turn it on. Your seal will be far less likely to be damaged during system start-up and will last much longer.

We do not claim that our check valves are self-priming, because we think the claim isn’t true and is in fact misleading. If you'd like to talk about check valve design parameters that do have an actual effect on check valve performance, please give us a call - we'd be glad to discuss!


Cartridge-type and rebuild-type check valves - which is better? 

Question: Optimize Technologies offers both cartridge-type check valves while some OEMs still use rebuild-type check valves. Which is better, and why?

Answer: For all of the HPLC pumps we support, we offer a cartridge-based after-market check valve system which has a series of benefits over rebuild-type check valves. Replacing whole assemblies in rebuild-type check valves means that you throw out the entire check valve housing and internal components, thereby replacing the assembly and installing a new one. This is expensive and wasteful. Rebuild kits are more economical, but the procedure is time-consuming and troublesome. Additionally, there is a risk of improper assembly and contamination.

Cartridge-based systems are, therefore, the preferable choice. They offer greater convenience, reliability, and economy, while reducing waste and risk of contamination during installation. Our OPTI-MAX Cartridge Check Valve System offers a number of other advantages, including a universal cartridge feature, the tightest leak-rate specification around, a choice of materials for cartridge and ball/seat, and much more.


How long can I expect my Optimize Technologies check valve to last? 

In general, you should be able to get a minimum of six months of good performance out of any check valve. With an Optimize Technologies check valve, you may get a year (or more) of reliable operation. Essentially, your mileage may vary depending on a number of factors, including operating conditions such as average back pressure, salt content of mobile phase, and flow rate.


What do I do with the Agilent 1100/1050 inlet check valve? 

The Agilent 1100 and 1050 both use a solenoid driven active inlet check valve. This check valve is that assembly you see sitting on the underside of your pump, right where the inlet line runs in. Replacing the entire assembly every time the pump needs to be serviced would get very expensive, so there is a little cartridge with the ruby ball and seat that is changed instead. While this makes it much more convenient and less expensive, it was not always this way. If you have a pump that is older and the inlet check valve has never been serviced, there is a good chance that you have an active inlet valve where the entire assembly must be replaced. Unfortunately, this is unavoidable. However, once the assembly has been replaced with the newer version, all subsequent service to the inlet valve can be done with replacing just the cartridge.


What OPTI-MAX cartridge type/material does Optimize Technologies recommend? 

For most applications, we recommend a stainless steel cartridge with a ceramic ball & seat. Ceramic is 1.5 times denser than ruby, and the heavier ball will seat more quickly, especially in lighter solvents.

Exceptions to this recommendation are as follows:

When aggressive organic solvents are to be used, consider PEEK cartridges. Stainless steel OPTI-MAX cartridges are equipped with Kel-F end caps, so switch to PEEK for the few cases where solvent compatibility with Kel-F is a concern.

Use PEEK cartridges with PEEK OPTI-MAX housings for biocompatible systems like the Waters 625/626 and Dionex systems.

Use PEEK cartridges when THF is present in the mobile phase. PEEK is uniquely suited for this application, as the material is thick enough to resist softening, and it is well-supported mechanically. We have been running PEEK OPTI-MAX check valves in 100% THF for a year to great success.


Why is there no filter in OPTI-MAX outlet check valves? 

Question: I notice that OPTI-MAX Cartridge Check Valves don't have a filter within the outlet check valve. Why not put a filter in there to catch particulates?

Answer: Some check valve designs incorporate a filter element within the outlet check valve. While in-line filtration is a worthwhile addition to any HPLC, putting a filter within the outlet check valve assembly has two major drawbacks.

First: a filter right above the outlet ball will concentrate particulates in a region where they can potentially cause check valve failure.

Second: the presence of an in-line filter element upstream from the pressure transducer can complicate pressure-based instrument diagnostics. We recommend the use of an in-line filter under all circumstances, but the best way to accomplish this is to install a separate filter assembly in-line downstream from the pressure transducer.

Pistons and Piston Seals

My HPLC makes a clunking noise. 

Question: I have a "clunking" HPLC (a ten-year-old Perkin Elmer 250 binary pump). This problem just developed in the last few days -- the "clunk" is not consistent, but develops if the pump is equilibrated at a low flow rate (0.2 mL/min) for a couple of hours and then put back into the operating flow rate (1 mL/min); if equilibrated at 1 mL/min, it takes a longer time (the whole day), but eventually the "clunks" start, albeit sporadically. No degassing problems, seal change 6 weeks ago, the flow is okay, the separation/current method is okay.... could this be the check valves? or something else? 

Answer: Does this pump have spring-loaded pistons? If you're hearing a pretty loud clunk, our first suggestion would be that one of the pistons is not following the cam all the time. Something is causing it to "stick" temporarily in the fully-displaced position, and the clunk you hear is the piston releasing and the base striking the cam. What can cause this, you ask? A too-tight piston seal can do it, as can precipitates on the piston.

But if the pistons are spring loaded, it is possible that a spring needs to be replaced. There is a possibility that salt has a better chance of building up at the slower flow rate.  Do you know which piston is clunking? Do you see any flow artifacts in the baseline when the clunking occurs? Our final suggestion is that the clunk could be coming from within the drive assembly itself, caused by a bearing or other mechanical part. At such a point, an in-person diagnosis would be best.


I put in a brand-new piston seal and it leaked. Any advice?

The way in which a seal is installed can have a big effect on how well it performs over its lifetime, or even whether it performs at all. Immediate seal failure is often caused by damage caused during installation. Most installation problems can be remedied with a combination of seal pre-soaking and wetting of all mating components prior to installation.

There other possible cause is a worn piston.  During routine use a seal and piston will wear together, and occasionally a flat or dull spot will be created on the piston.  When a new seal is installed the piston still has a worn spot and won’t be flush with the seal, which could cause leaking.  Our advice: replace your piston when you replace your seals.


Piston Seal, Solvent Compatibility Issues 

Looking for information on finding the best seal for your application? Want to know if there are potential interactions between the seal material and solvent you're using? Consult our Seal/Solvent Compatibility Guide.


What makes a good piston go bad? 

Abrasion! Your piston has a rough life - the piston gets crammed through a pretty tight aperture under high pressure ten, twenty times a minute, and the resulting friction will eventually abrade the piston surface. And if you're using buffers with inadequate piston washing facilities, the abrasive salt crystals will add to the abrasion. At some point, piston wear will reach a point where the seal is no longer able to contain the pressure around the moving piston. At that point, the piston needs to be replaced. Signs of wear/trouble include the appearance of scratches or haziness at the piston surface, flat spots, or other signs of unusual/uneven wear. 


What piston seal material should I choose? 

Optimize offers piston seals in two different materials - UHMW-polyethylene (our OPTI-SEAL® brand) and graphitized PTFE (our ITB™ brand.) The UHMW-PE material offers increased resistance to abrasion, and exhibits longer lifetimes in mostly aqueous mobile phases, especially when buffer salts are present. Graphitized PTFE offers a broad resistance to almost all common organic modifiers used in HPLC mobile phases (DMF can cause problems, though). For more specific information on seal/solvent interaction, view our Seal/Solvent Compatibility Guide, or contact Optimize Technical Support for a recommendation. 


What role do seal springs and O-rings play? Why are they there? 

Question:  There are seals with springs in them, and seals with O-rings. I've even seen a number of different types of springs in some seals. What does the spring do, and how important is it?

Answer:  The function of springs and O-rings in piston seals is to assist in actuation of the seal at low pressure. When you first start up your pump, it is the force of the spring that pushes against the outer seal wall and pushes the inner seal wall against the piston to form a seal. As the pressure inside the pump head increases, the hydraulic pressure of the mobile phase actually takes over the task of seal actuation, and at that point the spring is just along for the ride. This cross-over point can be anywhere from 250-400 psi, depending on the seal material and thickness. Of course, the pressure inside at least one of your pump heads is likely to be on a continuous cycle between system pressure and ambient pressure, so the spring still plays a role in keeping the seal actuated at low pressure during normal pump operation.


Which end of the seal goes in first? 

The spring cavity of the seal is energized by the hydraulic pressure of the mobile phase. Therefore, the side of the seal with the spring/spring cavity, or O-ring, should face toward the high pressure side. In the majority of pumps, this means putting the seal in spring-side first into the pump head, although some pumps reverse this orientation by requiring that the seal be pushed closed-side first into a bushing.


I already use a Solvent Reservoir Filter - why would I need an In-Line Filter as well?

Question: I'm filtering my mobile phase after preparation, and I use a solvent reservoir filter. Why would I need an in-line filter as well?

Answer: Running an HPLC pump without an in-line filter is not nearly as negligent as running your car without an oil filter, but the end result will ultimately be the same - increased maintenance and downtime due to damage from particulates. Your HPLC pump will introduce particulates into even the purest and cleanest of mobile phases. As the piston moves back and forth through the piston seal at high pressure, seal fragments can slough off from the mating surface of the seal. If you don't use an in-line filter, these particulates will end up clogging and/or causing damage to downstream components such as the injection device and analytical column. Placing an in-line filter in between the pump and injection device is possibly the most worthwhile filtration step you can take. Which would you rather replace every one to two months because of particulate clogging - a $500 analytical column, a $5,000 autosampler, or a $10 in-line filter frit?


Is precolumn filtration necessary? 

Question: Is precolumn filtration really necessary?

Answer: Two potential sources of particulate contamination can cause trouble in the region beyond the injection device but before the analytical column. First, the injection device itself can introduce particles resulting from rotor seal wear or the coring of vial septa. Second, contamination may be introduced by the sample matrix. Where practical, most of these types of contamination can be addressed in the sample preparation procedure. In cases where additional filtration is required between the injector and column, a low-volume, low-dispersion filter and/or guard column must be employed. OPTI-SOLV Mini Filters and OPTI-GUARD Guard Columns work extremely well for applications requiring precolumn protection.


Should I pre-filter my mobile phase? 

The first and easiest place to prevent particulate contamination is in the mobile phase. Buffer salts, improperly cleaned glassware, microbial contamination and pre-filtering procedures are all sources of particulates. Solvent manufacturers adequately filter HPLC-grade solvents prior to bottling, but the glassware it’s going into isn’t always clean. Ideally, there should be no need for additional pre-filtering in your laboratory if your mobile phase contains only HPLC-grade solvents, but it’s always better to be safe and use a Solvent Reservoir Filter. Mobile phases prepared with buffer salts or other solid reagents should be filtered prior to use, however. A 0.2 or 0.45 µm membrane filter is recommended for this filtration step. It is also a good idea to discard the first few milliliters of solvent that pass through the filter.


Should I use a solvent reservoir filter? 

Solvent Reservoir Filters are a useful filtration accessory, providing a first line of protection as the solvent enters the system. They also help to keep solvent tubing at the bottom of the reservoir. They are usually available in a variety of frit porosities. For analytical HPLC applications, a 2 µm frit is the best choice, while a larger porosity frit such as 10 µm should be selected for flow rates exceeding 10mL/min, in order to avoid starving the HPLC pump with too restrictive a flow path.


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