A chart recorder is an instrument that creates a paper chart record of the pressure in a system. It relies on ink pens mounted on mechanical arms, which pivot in response to pressure. Its primary advantage is an ability to record for extended periods in remote locations.
An experienced user may provide preliminary analysis on the chart output in the field, but communicating or storing the data electronically becomes possible only after a technician enters or scans the chart into a computer. This process can take days before results become available.
Chart recorders are bulky and heavy, and must be handled with extreme care. They rely on many moving parts that can degrade over time; especially in harsh environments, and especially if dropped. Even in normal conditions, pens can dry out and paper may be depleted or damaged by heat and humidity.
A Better Approach
Crystal has a better solution. The nVision reference recorder can collect and store up to 1 million data points at logging intervals as fast as ten per second. The data is collected electronically and stored in non-volatile memory, meaning that if the batteries deplete while testing, the data will not e lost. The batteries will last up to one year when in Ultra Low Power Mode.
The stored data can be viewed on the screen in an easy-to-read graphical format, or exported to an. xls, .csv, or .pdf file. You can even create a tamper-proof, secure signed .pdf file, which produces read-only files that cannot be manipulated.
The nVision is designed for rough environments. It contains no moving parts and can withstand dropping without damage. Each unit is IP67 rated, meaning it can be submersed in 1 meter of water for up to 30 minutes. Combined with its light weight and compact size, it is the unit of choice for pipeline companies doing work, from the cold in Alaska to the heat of Iraq.
Featuring 0.025% of reading accuracy, the nVision can provide deadweight tester accuracy in the field. Accuracy remains constant with temperature changes, is protected from high over-pressure events, and is not affected if the gauge is dropped. Unlike a chart recorder, if the nVision sensor is damaged, it will stop recording and thus prevent the chance of providing erroneous data.
Durability and Size – nVision
- No moving parts
- Drop-tested to withstand damage
- IP67 rated. (Submersible in 1 meter of water for up to 30 minutes)
- No additional equipment required
- Compact and light. 8″ (204mm) high and weighing just 1.5 lbs (680g)
Durability and Size – Chart Recorder
- Multiple moving parts
- Easily damaged if dropped
- Not IP67 rated. Susceptible to damage from moisture and harsh environments
- Requires paper charts which must be replenished, and pens that can dry out
- Bulky and heavy. Typically weighing from 25 to 70 lbs.
Accuracy – nVision
- 0.025% of Reading accuracy
- Accuracy remains consistent with temperature changes
- Protected from high over-pressure events
Accuracy – Chart Recorder
- 0.25% to 1% of span
- Ambient temperature and thickness of pens can cause an error of up to 1%
- Over-pressure and damage from dropping can add to the recording error
Reliability of Data – nVision
- Secure electronic records are downloaded using CrystalControl software
- Downloaded file is an easy-to-read, simple spreadsheet; or a signed, tamperproof .pdf that cannot be manipulated by the user
- Sensor ceases to record if damaged
Reliability of Data – Chart Recorder
- End result is a paper chart. If available, computer output is complex and costly.
- Interpreting paper chart data is subjective and requires training. Paper chart data can be easily manipulated by the user. (Tamper-proof pdfs are unavailable)
- Damage to the unit can go undetected, resulting in erroneous data.
I have seen the Crystal product in action and have spoken and worked with techs who have experience with this unit and it is definitely the way to go !!
Another homerun that should make work in the field much easier and much more accurate than before !
I have used and calibrated lots of chart recorders, and find them great to use in the field. They are great for remote locations with little or no power, they are easy to calibrate and replace parts.
this Crystal replacement sounds great but what does it need if it is going in remote locations with no power? And can it hold up to cold weather? most of the chart recorders I have worked on are running in approx -20C all winter
Thanks, Great information
It’s funny, I have worked with chart recorders and data-loggers for years and never actually considered replacing a chart recorder with a data-logger. It makes really good sense. We have sold chart recorders to both meat processing plants and refrigeration companies that need to keep detailed records of their processes. It’s probably time to convince them to move up the technology ladder.
My company has been using this product for a while now and i am continually impressed by its versatility
thanks for the info. we occasionally require recorders for our ph adjustment systems, I will keep this in mind.
Use the nvission often, really like the product.
Looks excellent. I have no experience with the nVision but would use with confidence based on this post.
Is the product available with any safety certification(s) for hazardous location use?
Small typo in the text under “Reliability of Data”-“Chart Recorder”: “paper chard” instead of “paper chart”.
Thank you for the feedback Michael. I’d like to address the two points you have noted.
1. When the nVision is running in Ultra Low Power Mode you can record for up to 60 days on a set of 4 AA batteries (2 modules recording at 5 min intervals in 23C ambient temperature)
2. The unit is temperature compensated from -20 to 50C meaning the readings will be in spec when measuring between these temperatures. There are also many examples of people using these instruments in much colder weather. The display is often the first thing to stop working in extreme cold, but the nVision is able to continue recording it’s readings.
All the the above information can also be found at: http://www.crystalengineering.net/files/4791%20Rev%20I%20nVision-PSI%20Data%20Sheet.pdf
Please let me know if you have any further questions or comments.
Thanks for the reply Tom. We do have rental nVision units available, if you are interested in giving them a try. Give us a call to discuss. 1.888.863.8010.
Hello Robert,
Thank you for the text correction. I’ve made the change.
To answer your question regarding the safety certifications for hazardous location use, yes, the nVision is Intrinsically Safe. It has CSA Approval and is listed as Exia Intrinsically Safe and Non-incendive for Hazardous Locations: Class 1, Div. 1, Groups C and D, Temperature Code T4/T3A/TCB/T3C for hazardous locations product warnings, refer to the operation manual: http://crystalengineering.net/files/4701%20Rev%20L%20nVision%20Manual.pdf
I hope this information helps. Please don’t hesitate to contact us for more information.