Myths and Truths About Multi-Input Analyzers

Key Words
multi-input analyzer, water quality, instrumentation, water, waste water, process industry, efficiencies, digital controllers

Today`s process world is a challenging one. Plant managers, metrology labs, and maintenance workers are constantly asked to improve their process efficiencies and output while at the same time seeing their budgets, manpower, and workforce reduced.
Fortunately, companies that serve the process industry have used these imposed limitations as an impetus to improve their products to help meet these challenges. You don`t have to look very far to see these product improvements in action. Product features like fault tolerance, predictive sensor analysis to aid maintenance or self-healing in networks so data is not lost are all examples of product enhancements that deliver more value to the process industry.

Multi-input analytical instrumentation is not a new idea. For over two decades, many different types have come and gone only to leave confusion and misinformation in their wake. How does one separate the fact from the fiction?

By keeping in mind a few simple requirements it`s not only possible to find what you need fa your process but also find a product that will meet those needs for years to come.

The Online Process Analyzer
One of the products that has seen an accelerated evolution is the online process transmitter/ analyzer. The online analyzer has been a fixture in the process world since there has been a requirement to make a measurement, provide a local display of that measurement and then later transmit that reading to a remote location. Over the years these instruments have evolved from local visual levels, analog dials, or audible devices to highly-advanced electronic processor-based instruments capable of making many measurements easily, accurately, and with high speed all in one device.
Recently, the trend has been to provide analyzers with multiple channels in one device. This concept is not a new idea by any means. As soon as analyzers started to use solid state electronics, the idea of providing an instrument that can make more than one measurement was a natural evolution. Unfortunately, these first designs were flawed and suffered from two major drawbacks. First, they were very complicated thus making them hard to maintain. And second, they tended to be very expensive.

Despite these drawbacks, the process industry did see the value in consolidation and tried to adopt the concept. However, it was discovered that failure of the systems was common because of the complexity of the devices, and the problem was compounded due to loss of not one but two or more measurement points. This, in turn, led to some costly production downtime so the concept ot multi-parameter meters died as an unreliable and risky venture.

Enter today`s multi-parameter meters. Manufacturers have returned to the concept of multiparameter meters largely due to the process world`s constant demands. Learning from the mistakes of the past, manutacturers are producing reliable and flexible instruments thai not only fill the requirements of the process industry, but are also redefining how process measurement is done.

Choosing the Right Multi-Parameter Meter
Almost every manufacturer of process instruments now makes a multi-parameter meter. The question is which one is right for your needs and your process? The key to picking a good multi-parameter meter is to make sure ft meets some basic requirements. Here are some important features to consider.

• Make sure the parameters are modular
  While there are many process analyzers that are "multi-parameter, most are predefined instruments that are integral components to the entire device. Meaning, they are designed and manufactured as one instrument. While this may keep the cost down it unnecessarily puts you at risk. If one channel goes bad in instruments like this you are forced to either revert to using the meter as single channel device or having to replace to whole instrument even though one of the channels is still operating properly. That lower price isn`t looking so good now, is it?
• Make sure the power supply is also modular
  Just like the channels, it is just as important that the power supply be modular, as well. One of the most vulnerable parts of an analyzer is the power supply. We all have heard of or experienced situations where electrical storms or power surges have left process analyzers inoperable. An advantage of a modular power supply, is that it`s a lot easier to replace a single component of the analyzer, rather than replace the whole device. Not to mention the cost savings. This is a key feature that not many analyzers offer.
• Make sure that the parameter modules have the option of both analog and digital signals from the sensors
  While you will find that there are many manufacturers that have multi-parameter meters, almost 70% of them will only work with digital sensors. What does that mean? That usually means that the only sensors that will work with the meter are the ones that the analyzer manufacturer supplies. Proprietary digital protocols lock you in essentially into using only what the manufacture has chosen to support. While in some cases this might be ok, there`s a risk of losing the flexibility to choose the sensor that works best in your process. Having the choice of analog modules keeps your options open, so you don`t have to compromise when it comes to finding the best solution for your application or process.
• Choose an analyzer that has multi-function module slots
  While it`s nice to know you have open slots for other sensors, it`s even better when those same slots can accept other options. Additional relays and digital communication protocols (i.e. MODBUS®, Profibus™, Ethernet, etc) add to the flexibility of the whole platform. While you may not need it now, you`ll appreciate the flexibility of your system as your business grows and evolves.
• Choose an analyzer that has updateable firmware
  By having the ability to update the firmware, you can get the latest and greatest features or improvements and usually at no additional cost. In addition, while most firmware is vetted pretty well, there is peace of mind knowing that if there is a bug discovered, you`re not stuck with it until you replace the meter.