Cambridge Viscosity Blog

When it comes to air conditioning and compressor systems, achieving ideal operating efficiency is about balance. Too much lubricant means the compressor or cooling system won’t cool properly, and too much refrigerant increases bearing wear and reduces the system life. Thicker oil lubricates better, but it also means there is an increase in drag, and more power is needed to rotate the compressor. Manufacturers must consider all these variables when manufacturers designing their equipment. Each new design requires significant testing to ensure performance and energy efficiency.

The right refrigerant/lubricant mixture means optimal performance of the compressor, so knowing the viscosity of the blend is extremely important. Viscosity is a function of pressure, temperature, and solubility. All three are needed for compressor design. 

Daniel charts use equations of state to determine the relationship between viscosity, temperature, pressure, and solubility and are used to profile lubrication/refrigerant pairings to ensure optimum performance and efficiency. Cambridge Viscosity’s viscometers are the industry standard for Daniel chart development.

A Daniel chart profiles the relationship between pressure, temperature, and solubility

 

Cambridge Viscosity's VISCOpro line of micro process viscometer’s includes the only sensors that are small enough to be installed directly in the compressor pump. In addition to being extremely small, the viscometer is flexible enough to work with proven accuracy and reliability under a wide range of pressures and temperatures. In a typical installation, the 571 sensor or 501 sensor is mounted directly in the compressor pump or pressurized line, where it captures continuous viscosity and temperature measurements through the test cycle.

The CVI viscometer is unique in its ability to measure low volumes at high temperatures (190 °C) and high pressures (2000 psi+).

Results 

• Robust measurements under pressures exceeding 1000 psi and temperatures up to 190 °C
• Highly repeatable measurement — better than  0.8% of reading
• Low sample volume requirement
• Smallest sensor in the industry
• All 316L stainless-steel, wetted parts
• Accuracy (1%)

 

When compressor manufacturers design a new compressor model, part of the process includes determining the type of refrigerant and the accompanying lubricating oil, which is necessary to reduce friction on metal parts, reduce wear on the compressor, and extend the life of the system. The company must conduct extensive testing to ensure proper energy efficiency and functionality. The lubricant has a significant impact on the performance of the compressor. Over-lubrication can impact the compressor’s ability to cool properly, but too much refrigerant will lead to more wear and a shorter compressor lifecycle.

Recently, a group of researchers, Jianhua Wu, Zhenhua Chen, Jie Lin, and Jinbo Li, from Xi’an Jiaoton University published a paper titled “Experimental analysis on R290 solubility and R290/oil mixture viscosity in oil sump of the rotary compressor”. They conducted a set of experiments on both the compressor performance and system psychometric chambers for an R290 rotary compressor with mineral oil having high viscosity.

Window-unit air conditioners that are often used in homes usually apply rotary-type compressors with a high-pressure shell containing various types of bearings, pistons, and friction shells. The functionality of these bearings and friction pairs is an important factor for the performance and reliability of the compressor. The viscosity of the lubricating oil and refrigerant mixture depends on the solubility of the refrigerant in the oil at a given temperature. When the refrigerant is more soluble, the viscosity in the oil sump will decrease. If the lube oil/refrigerant mixture stays at a low viscosity for an extended period of time, bearing wear will increase, leading to problems.

The researchers wanted to better understand the variables affecting operating viscosity of oil with dissolved refrigerant – specifically for R290 which is a feasible alternative to the more common R22 or R410A in residential air conditioners. One of the challenges they faced was obtaining accurate, real-time refrigerant solubility and mixture viscosity in oil sump using only the saturated mixture properties. In the research, they took a look at the practical solubility and viscosity of R290 refrigerant in mineral oil with a high viscosity grade.

For one of their experiments, they installed a VISCOpro with a SPC501 sensor at the bottom of the compressor to measure the viscosity of oil before it entered the crankshaft hole. The accuracy and reading error of the viscometer were +/- 0.1% and +/-0.8% respectively.

 

 

The 290 refrigerant is flammable, and they wanted to know if it could be safety used in compressors, and if it would perform correctly, making it a viable alternative for traditional refrigerants. Without the VISCOpro, the researchers were able to make theoretical calculations that allowed them to make predictions offline. With the VISCOpro and SPC501 sensor, they were able to make empirical measurements in real time.

In order to capture in-line measurements, they required a small, rugged, robust instrument that would handle the temperatures of the sump and the actual operating conditions. The VISCOpro, with a viscosity range of 0.2-20,000 cP and an accuracy of greater than 1%, helped the research team successfully complete their research project.

 

 

The entire paper was published in the International Journal of Refrigeration is available for purchase online through Science Direct at https://www.sciencedirect.com/science/article/abs/pii/S0140700718302718.

The VISCOlab PVT is a high-pressure, high-temperature viscometer. It is no secret that we are pretty proud of it. The PVT is a great product. It has the widest temperature range, the widest pressure range, and the widest viscosity range of any viscometer on the market. When you want to achieve accurate viscosity measurement under conditions of extreme pressure and temperature, the VISCOlab PVT is your viscometer. 

Recently, our marketing department — and specifically, our Houston-based marketer Peter Vogel — put together this very cool video for a campaign. With just two calls with highly technical engineers and little creative guidance, Peter was able to conceptualize a very loose idea and turn it into this video. We love it. Excellent work, Peter!

If you have 29 seconds, we'd love if you watched the video and let us know what you think. 

 

The need for accurate and reliable viscosity measurement in high pressures and temperatures spans many applications across multiple industries. Oil exploration, enhanced oil recovery, and bearing analysis are just a few.  Cambridge Viscosity has a long history of meeting these challenges. The key is in the SPL-440 sensor, which is the heart of the VISCOlab PVT. Our new white paper touches on why viscosity measurement is so important when it comes to applications like oil extraction. 

Download the White Paper: Achieving Accurate Viscosity Measurement in Conditions of Extreme Pressure and Temperature

 

If you have any questions about small-sample viscosity measurement or want to chat about your specific application, feel free to reach out to us. An application engineer will get back to you within one business day. 

If there’s anything that we’ve learned in 30+ years of business, it’s that our customers are smart. Often, you’re the best in your field. You know your industry as well as you know the face looking back at you in the mirror.

And you know exactly what you need from a viscometer.

The challenge lies in knowing what viscometer manufacturers offer, and how many boxes different viscometers check on your needs/wants/nice-to-have list.

We get it. And because our job is to reduce your challenges, we created an easy-to-use, 7-step configuration guide to help you figure out how to configure your Cambridge Viscosity VISCOpro 2100 viscometer.

It’s a simple process, but we’ll walk you through it. First, we recommend printing it out.

 

 

Section 1: Electronics

The first step is to select your electronics configuration. You have 2 options. If you’re in a safe area, like a lab, you’ll probably select E1, DIN-Rail Mounted. Write “E1” in the gray box

If you work in an explosion-proof area, you’ll need explosion-proof housing. Write “E2” in the gray box.

 

 

 

 

 

 

Section 2: Application Packages

We have three available performance packages – Basic (or Core), Advanced, and Plus. If you look at page 2 on the configuration guide, we’ve provided some additional features of each option so you can select the level that is best for your specific application.  Write CV1, CV2, or CV3 in the orange box as appropriate.

 

 

 

 

 

Section 3: Temperature

The VISCOpro 2100 can be configured to meet your specific temperature requirements. Our low-temp option is for applications that have a maximum temperature of 190 °C, while our high temperature option has a maximum temperature of 375 °C.

We’re going to jump ahead for just a minute, because your choice of high or low-temperature viscometer will impact the sensors you can select. In Section 5, you’ll be able to choose your process connection. High temperature options include C1, C2, C6, C7, C8, C9, C10, C11, C12 and C14. Write your section in the medium gray box.

 

 

Section 4: Area Classification

The VISCOpro 2100 is compliant with many hazardous area certifications. Section 4 allows you to specify if any of those classifications is a requirement for your viscometer. You can select from ATEX (A1), NEC (A2), IECEX (A3), Safe Area (A4), or CEC (A5). Write your selection in the royal blue box.

 

 

 

 

 

 

 

Section 5: Process Connection

Section 5 is probably the section you’ll give the most thought to – this is where you select your sensor. The 2^nd page of the configuration guide offers further detail on each option. We’ve developed a wide range of sensors to meet the varying needs of our customers and varying piping specifications. For example, if you selected a high-temperature viscometer, your best options are C1, C2, C6, C7, C8, C9, C10, C11, C12, and C14. Occasionally, we come across applications that require a custom configuration. If this is the case for you, feel free to reach out to our application engineers to talk shop and determine what you need. Otherwise, write your selection (C1-C14) in the dark gray box.

 

 

 

Section 6: Viscosity Range

The VISCOpro 2100 offers viscosity ranges in 20:1 spans covering 0.25 to 10,000 cP. For section 6, write your required viscosity range section (2-12) in the light blue box.

 

 

 

 

 

 

 

 

 

 

 

 

Section 7: Options

This section allows you to further customize your viscometer by selecting a few options, such as a longer cable, high or standard pressure, body length, temperature jacket, in-tank stem length, or piston material. Check the boxes as necessary, and ignore the ones that don’t apply to your application.

 

 

 

 

 

 

 

 

You’re done! The completed guide will generate a code, for example, E1-CV3-LT-A4-C4-7. Just email the completed form, or even just this code, to sales@cambridgeviscosity.com, and we’ll call you back within 24 hours to discuss your viscometer further. (You can send the completed pdf, or if you wrote it out by hand, just snap a photo.)

 

A refinery was interested in increasing the production of their lubrication products by reducing the time it takes to formulate the products. The facility had several blending tanks in varying sizes, which were used for blending multiple products. Their operating procedures required that they test samples from the top, middle, and bottom of the tanks to ensure the samples were homogenous. Because they didn’t know the exact blending time of the batches, their procedures required that they wait for an hour or more to be sure that full blending had occurred. This effort was time-intensive and could add 45 minutes or more to a batch. If the mixing wasn’t complete and the tests needed to be performed again, even more time would be added to the process.

We were sure we could help them out.

At the invitation of the customer, Cambridge Viscosity performed a trial to help the process engineers determine how quickly the fluid in the tank became homogenous during the blending process. CVI installed two VISCOpro viscometers with model 321 sensors on a single three-meter stem and inserted the stem into a lubricant blending tank from the top.

Prior to the test, CVI and the engineers discussed whether installing two viscosity sensors (installed at the top and bottom) or three viscosity sensors (installed top, middle, and bottom) would be necessary to determine if the mixing was complete, because they were not sure how quickly the mixture became uniform. It was decided that a custom viscosity probe with sensors installed at the top and bottom would be the best option for testing. (See illustration to the right.)

The results of the test showed that blending was complete significantly earlier than expected, which allowed them to perform final quality control procedures and transfer the product up to 30 minutes earlier. Additionally, they found that there was little stratification and that both the upper and lower viscometers showed that the fluid reached the target viscosity within one minute of each other.

The facility selected a final configuration that consisted of a two-meter probe with a single model 321 viscosity sensor for each tank. During the process, the viscosity is monitored in the tank until the values plateau and then a sample is sent to the lab for final quality control before transfer for shipment. This method reduced the manufacturing time, which led to increased output capacity, reduced demand on the lab, and improved QA traceability.

The CVI viscometer helped the refinery meet several goals, including:

• Reducing lubricant blending time by more than 30 minutes
• Increasing output capacity
• Reducing demand on the laboratory
• Enhancing QA traceability

The CVI application engineers are ready to tackle your unique applications. If you’d like to discuss an idea, application, or challenge, fill out the form and we’ll get back to you asap.

Maintenance is more than fixing problematic equipment. A preventative maintenance program for your lab or process equipment can help you minimize unplanned downtime and maximize efficiency. All instruments operate best when routine maintenance is conducted, and this is true for Cambridge Viscosity viscometers. Even when a CVI viscometer is working perfectly, we recommend a yearly service inspection. To ensure equipment health and optimum performance, CVI viscometers should undergo annual servicing that includes:

• Annual inspection
• Cleaning
• Verification of settings
• Reviewing historical data and error logs
• Calibration verification

Making the shift from corrective maintenance to planned maintenance is often easier discussed than implemented. Often, the people who are conducting the instrument maintenance carry many responsibilities, and finding the time for preventative maintenance is a challenge amidst larger issues.

Preventative maintenance contracts are less expensive to purchase than the emergency repairs they are preventing—and that doesn’t include your cost of downtime. 

CVI is pleased to announce that we’re again offering On-Site Service Contracts to support the ongoing health of installed Cambridge viscometers.

On-Site Service Contracts include options to fit your needs:

• Annual onsite maintenance, scheduled at your convenience
• No-charge software upgrades as they become available
• Discounted parts and accessories (15%)
• Extended phone support
• 24-hour turnaround for most spare parts
• Discounted training programs (15%)
• Loaner viscometer to minimize downtime

 

Covid-19 prevented our on-site for the last year, but as the vaccinated population continues to increase on schedule (or ahead of schedule), we are expecting to resume our field services in May. There is still some uncertainty, so we are not scheduling site visits before June 15, 2021.

Call 1-800-444-TEST today or email ProcessService@PACLP.com to schedule routine maintenance either at our depot or your facility, and ask if the On-Site Service Contract is right for you.

When it comes to rotating equipment, it’s a question of when—not if—a failure will occur. Engine breakdowns, for example, are often caused when the bearings in rotating parts fail. What does this have to do with viscosity, you may be wondering. Faulty bearings can generally be traced to one of three issues: 1) Severe service conditions, 2) improper handling or installation, or 3) poor lubrication.

Improper lubrication, in fact, can be traced back as the root cause of the bearing failure about 50% of the time. This can occur when the lubricant’s lubricating properties are insufficient. Bearing failures can frequently be traced to viscosity breakdown as a result of fuel dilution, additive oxidation, soot, water, various other contaminants, or thermal degradation.

Cambridge Viscosity VISCOpro 2100 oil condition sensor (301), monitors the viscosity of the lubricating oil to prevent viscosity breakdown. Because viscosity is an indicator of oil health, real-time, dynamic viscosity measurements and trending can provide an early warning of oil and equipment failures.

By providing data that can be used for immediate intervention, the VISCOpro 2100 helps to prevent serious problems.  Typically, maintenance personnel regularly send samples to off-site laboratories for analysis or change the oil on a scheduled basis. The VISCOpro 2100 reduces the amount of laboratory sampling that is necessary, and the continuous online monitoring allows operators to catch a problem with the lubricant before it becomes critical and leads to failure. Also, it allows operators to increase the interval between laboratory checks and lubricant changes.

The VISCOpro 2100 is particularly good at detecting fuel dilution, which is a critical parameter, and difficult to measure with any other technology.  The VISCOpro is the only sensor available that can detect all the parameters of fuel problems, like fuel dilution, additive oxidation, soot, and water.

It is a rugged, accurate, and repeatable technology, even in environments with heavy vibration. The motion of the piston monitors the fluid viscosity and keeps the sensor’s measurement chamber free of debris, so the sensor doesn’t require operator intervention. It includes a temperature detector, allowing the capture of both temperature and viscosity in each measurement.

Results:

• Detect small changes in viscosity in real-time, even as low as .25% fuel dilution
• Avoid bearing damage in between lab analyses
• Incorporate temperature compensation to adjust for normal temperature effects on viscosity readings
• Expand lab testing intervals
• Extend periods between oil changes
• Best technology available for detecting fuel dilution

 

The need for accurate and reliable viscosity measurement in high pressures and temperatures spans many applications across multiple industries. Oil exploration, enhanced oil recovery, and bearing analysis are just a few.  Cambridge Viscosity has a long history of meeting these challenges. The key is in the SPL-440 sensor, which is the heart of the VISCOlab PVT. Our new white paper touches on why viscosity measurement is so important when it comes to oil extraction. 

Download the White Paper: Achieving Accurate Viscosity Measurement in Conditions of Extreme Pressure and Temperature

Here's an excerpt.

Extracting crude oil from the fluids underground is a complicated task. Oil companies must have a solid understanding of the fluid’s characteristics in order to make informed decisions. The ability to measure the viscosity under reservoir conditions helps them assess the quality of the oil, as well as the best extraction, production, and processing methods of these heavy fluids. The potential for variability in oil is high, and oil companies must understand fluid mobility and changes to mobility under changing pressures and temperatures. 

When pressure falls, gas condensate liquid dropout can occur in gas reservoirs, which can affect well production. Oil and gas companies need to understand the point of dropout, but extracting a sample is extremely difficult. Samples must be pulled from rock deep below ground, which is an expensive endeavor, and one that often yields a limited sample volume. The challenge of sample collection makes it hard to obtain viscosity data. Understanding viscosity as a fluid property is required in reservoir simulation and engineering calculations. Errors in reservoir fluid viscosity result in errors in cumulative production.  That means a negative impact on profit.

To accurately simulate downhole conditions in an oil reservoir, oil companies require accurate viscosity measurement under extreme pressure and temperature conditions.

In the past, when there was a need to measure viscosity at extremely high pressures and temperatures, solutions were limited. It wasn’t uncommon to run into homegrown, proprietary measuring systems that tended to be massive, and understood and operated by only the small number of experts who actually built the machine. If they left the company, no one would be left who could operate and maintain the system. 

It was this type of scenario that led Cambridge Viscosity to develop the VISCOlab PVT™. A company who performed analysis on petroleum hydrocarbon fluids wanted to analyze live oil samples. They wanted to use small sample volumes and achieve extremely accurate measurements without using mercury. And the viscometer had to be able to handle very high pressures, and both high and low temperatures. 

Fill out the form above to read the entire white paper. 

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If you have any questions or want to reach out to us directly, please fill out this form. 

Managing lubricant viscosity is essential to maintaining the health of a compressor in a process plant, because a single compressor failure can cost $10,000 a day or more in lost revenue. Considering it’s another $10,000 to rebuild a compressor, or more than $100,000 to replace a compressor, maintaining the health and performance of compressors is important.

Many factors affect lube oil viscosity:

• Oxidation occurs when churning lube oil foams, exposing more oil to surface air and causing oxidation, which lowers viscosity and threatens useful lubricant life.
• Dilution results when lubricant oil is diluted with gas, such as methane, dropping viscosity.
• Bubbles form as foaming oil churns against the screws or vanes of the compressor, instantly dropping the viscosity of the oil.
• Contamination occurs when hydrocarbon vapors in the process mix with the lube oil

The situation can be further aggravated by significant changes in temperature  – such as during start-up – that affect the viscosity of the underlying lube oil. A range of compressor failures can result. Rotary and thrust bearings can fail, which in turn causes wear on the rotor assembly. Replacing bearings is less costly than a total rebuild or replacement, but either way, the plant faces downtime.

While refineries commonly perform monthly lab checks, the unpredictability of viscosity changes means that these monthly checks are not enough to prevent bearing failure and subsequent plant downtime.

 

“Despite using separators, the lubricant can become diluted by gas carry-over or contamination. If left unchecked, this can cause problems, especially during subsequent start-ups.” 

- Lead Engineer, Gulf Coast Refinery

 

Preventing Bearing Failure and Downtime

Refineries are finding that that monitoring lubricant temperature isn’t sufficient to protect compressor bearings, especially in applications where process starts and stops can occur. Despite using separators, the lubricant can become diluted by gas carry-over or contamination. If left unchecked, this can cause problems, especially during subsequent start-ups. 

Refineries can protect their large hydrogen screw compressors to improve refinery uptime by adding in-line lube oil viscometers to all their new and existing units. In-line, in situ viscosity monitoring provides plant operations with real-time data on the lubricant viscosity.

The VISCOpro 2100, along with a 301 in-line viscometer sensor, provides real-time continuous monitoring of the compressor bearing lubrication fluid throughout equipment operations.  This saves lab and technician time, and reduces the chance of damaging the equipment.

Results

• Save $10,000+ a day by avoiding unplanned shutdowns caused by compressor failure
• Identify contamination, oxidation, dilution, and bubbles
• Monitor viscosity across wide temperature swings
• Measure under pressures of 1,000 psi and temperatures up to 190 °C

 

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What is viscosity?

Viscosity is an important characteristic of a liquid which helps predict its flow behavior.  It quantifies a liquid’s internal friction, determining its resistance to flow.  The higher the viscosity, the slower the flow.

 

Why is it important for coatings?

Coating companies use viscosity as a means to measure and control the percent solids in coatings, establishing their coat weight thickness.  Standard practice has been to maintain a constant cup viscosity target, day and night, summer and winter.  Viscosity is directly related to temperature, so to measure one without taking into account the effects of the other is inadequate.  For example, 70 secs @ 70°F, vs. 70 secs @ 100°F are dramatically different and produce significantly different coat weights.  The first example yields very light coat weights, the second, very heavy coat weights.  A temperature spread this large would probably yield out of spec product.

 

 

How is viscosity measured?

In the past, the cup method was a popular method of viscosity measurement in the coating industry.  Using this method, an operator dips a cup into the can coating material, and then uses a stopwatch to measure the time it takes for the fluid to flow through a hole in the bottom of the cup.  The longer it takes, the higher the viscosity.  It is a simple approach. However, in a situation with many operators, there are many different variations on the basic method of measurement, and therefore there are many different measurements.

 

Results obtained with the cup method are inaccurate and are not repeatable even if the same person makes measurements all the time.  Cups are just not accurate or reliable for today’s coatings, and that is why most professionals in the coating industry are installing process viscometers.

 

How do I know if I need a viscometer?

 

If you don’t have any problems with your coating process, and if you are completely satisfied with your finished quality and costs, then you don’t need a viscometer.  If, however, you would like to improve your process, improve your quality and save money, then a viscometer can help dramatically.

 

What should I look for in a viscometer?

Process viscometers can be excellent additions to the coating process. However, not all viscometers are created equal. Traditional process viscometers have been used in many coating applications, and although they are better than cups, there are still significant problems with accuracy, reliability, and repeatability.

 

The main problem with traditional process viscometers is the wet/dry interface.  Process viscometers are usually mounted in a coating tank with a constantly changing coating level.  Every time the level goes low, the coating dries, promoting a buildup on the traditional rotating spindle or a piston rod.  This is especially true for today’s water-based coatings which do not go back into solution after they have dried.  As the coating builds up on the viscometer, the drag on the viscometer is higher and the viscosity number goes up artificially.  The unit makes an adjustment to thin out the coating when it shouldn’t, resulting in bad product and lost production.

 

What’s different about viscometers from Cambridge Viscosity?

Viscometers from CVI provide a unique solution to the problem.  Based on a patented piston sensor design, Cambridge viscometers are accurate, reliable, and require little or no maintenance for most can applications.  For example, the ViscoPro 2100 accurately measures viscosity and temperature and calculates TCV (temperature compensated viscosity), the calculated value of viscosity at another temperature.  TCV is an important tool that accurately indicates if percent solids have changed, allowing plant personnel to eliminate the effects of process temperature variations on viscosity readings.

 

What does the systems consist of, and how is it installed?

The CVI viscometer system consists of a sensor, piston, cable, and electronics. The sensor is rugged and simple in design, and the electronics are easy to use. Also included are 4-20mA outputs for both temperature and viscosity which can be connected to a monitoring and control system.

 

Installation is simple and inexpensive.  Simply add a “tee” fitting into the existing coating line going to the applicator.  Install the sensor and run the cable back to the electronics.  The electronics come in an explosion-proof rated NEMA4 enclosure for protection or DIN-rail-mounted housing, which can be mounted hundreds of feet away if necessary.  Install the valves for your water addition and wire the solenoid back to the electronics.  It’s that simple.

 

What about maintenance?

Cambridge Viscosity viscometers are designed to be maintenance free.  A simple field calibration is recommended for most applications.

 

How do I know it will work?

CVI systems are currently operating well in coating applications across many industries, including optical lenses, medical applications, automobile headlights, telescopes and cameras, and many others.  Additionally, Cambridge Viscosity systems are guaranteed to perform to your satisfaction, or the system can be returned within 30 days for a full refund.

 

To ensure your success, CVI personnel will provided continued consultation after installation and make certain that it is installed correctly, and that its operation is understood by line personnel.

 

How do I order a system from CVI?

Cambridge Viscosity application engineers are available to discuss your specific needs.  First, you can build your viscometer by clicking the Build your own viscometer button below.

A member of our customer support team will contact you to discuss and clarify any areas as necessary, and a quotation will be generated.

 

 

 

Have questions?