With so many test instruments to choose from, how do I find the right one for my application?
First, it is necessary to define the physical, electrical or chemical parameters to be measured. In other words, to measure temperature, a thermometer is needed. If weight must be determined, a scale or balance is required. When the parameters are not so clearly defined, often you can look to your industry's standards or best practices for guidance. If the substance or material to measured is new or has yet to be identified, a variety of test instruments may be required to determine the characteristics for classification. For example, a metal can be characterized by its conductivity, magnetism, hardness, etc.
How often will the test instrument be used?
For test instruments used daily, reliability is paramount. Nothing is more annoying than when a device is out of service, especially when there is no backup device on hand. Of course, reliability is important even for test instruments that are used sporadically. PCE Instruments stands by the reliability of its test instruments by offering a two-year warranty against manufacturer defects. Unfortunately, some test instrument manufacturers will sacrifice reliability and other features for cost savings. This leads to the following question:
What features are required?
Different test instruments have different features. These features may be:
- Data memory: A test instrument may or may not have the ability to save measurement data. If a test instrument has memory, the memory either can be found internally (i.e., built into the device) or on a removable SD card. In addition, the memory size will differ greatly. For example, if a test instrument is meant to be used for long-term monitoring, the memory size will be much larger as the instrument will need to store more measurement data. If a test instrument solely is meant to take readings on the spot, the memory size will be significantly smaller as the instrument will need to store much less data.
- Data logging: This feature allows for long-term monitoring. Measurements are taken at a specific interval (e.g., once every second, twice per minute, etc.) over a period of time. Often the frequency and length of the interval is adjustable and can be programmed to meet the unique needs of the application. After each measurement is captured, a date- and time-stamped record is saved to and stored on the memory.
- Data interface: To transfer measurement data to a PC, printer, laptop or smartphone, a data interface is required on most test instruments. Common data interfaces typically available on test instruments are: USB, RS-232, RS-485 or Bluetooth. However, test instruments with a removable SD card memory are an exception. A test instrument with an SD card memory does not necessarily require one of the aforementioned data interfaces to transfer measurement data, as the SD card itself is the vehicle for data transfer. The SD card can be placed into an SD card reader to transfer the measurement data.
- Filter: Some test instruments offer the possibility to filter the displayed measured value. For example, in a sound level meter, the displayed measured value might be filtered over an A- or C-weighted frequency. In a wind speed meter, the displayed measured value could be filtered by the maximum, minimum or average wind speed.
Another important feature to keep in mind is the level of service and support provided by the test instrument supplier. Different test instrument suppliers provide different levels. To find out what kind of support will be available to you as a customer, call the supplier and talk to the technical support team prior to purchasing to see for yourself the level of service provided. Also find out how long the supplier has been in business. The longer the company's tenure, the more likely it is that you will be able to order spare parts a few years down the road after buying your test instrument.