Meriam HVAC Equipment and Instruments
This product category includes airflow capture hoods (or Balometers) and various types of manometers.
An airflow capture hood is a device used for measuring the volume of air coming out of grilles and diffusers in HVAC systems. Airflow capture hoods make taking these measurements much easier than ever before because they use a one-step, direct volume measurement. The fabric skirts and frames of for these instruments can be found in a variety of sizes to fit any grille or diffuser.
Manometers are instruments used to measure low pressures, such as duct static pressures and differential pressures. Today these instruments are almost exclusively digital. Digital manometers completely eliminate liquids and replace them with either absolute, vacuum, gauge, or differential pressure sensors. This makes the modern manometer extremely versatile because it can be used in any position and does not require leveling.
This product category contains analog and digital HVAC manifolds, gauges, and draft gauges.
A draft gauge is essentially a manometer used to measure draft of low gas heads, such as draft pressure in a furnace, or small differential pressures of less than 1 psi. These instruments are suitable for checking flue pipe, chimney, fire box, smoke hood, smoke pipe draft, draft regulator, oil burner firing rate, and basement ventilation.
Manifolds are used to monitor and charge HVAC systems. These units will have multiple ports for different refrigerant types. The majority of these units are simple analog instruments. However, there are many digital manifolds on the market today that enable the user to perform other complex operations such as calculating superheat and subcooling, linear adjustment of the pressure sensors, and micron measurements via a built-in micron gauge.
Gauges are simply used to monitor HVAC systems. These can range from simple analog gauges to digital vacuum gauges with built in high and low pressure alarms and integrated timers to record how long the system has maintained a deep vacuum.
A vacuum pump is used to remove air and contaminants from an HVAC system after refrigerant recovery. This creates a vacuum state. The deeper and more complete the vacuum, the more contaminants trapped within the system, its components, and even the compressor oil are removed. A vacuum can help protect your system from contaminants and non-condensable gases which can damage HVAC system components, reduce system efficiency, and even cause failure. Make sure you recover, repair and check for leaks before pulling a vacuum in your HVAC system.
Instruments in this category do exactly what the name suggests: they detect refrigerant leaks. These instruments use a variety of methods to find leaks. Common methods today include infrared, heated diode, and corona discharge.
Both heated diode and corona discharge (while technically different) operate in a similar fashion because they both use two electrodes in their sensors. These determine leaks based on refrigerant concentration or current drop between the two electrodes.
IR leak detectors are entirely different. These instruments work on the principle that refrigerants reflect a certain infrared frequency of light. When refrigerant is drawn into the sensor, it travels between a light/heat source and a sensor. When the refrigerant reflects the infrared radiation and blocks the sensor an alarm is triggered on the detector. These units have many advantages over other leak detectors.
Refrigerant recovery machines are used to remove refrigerant from cooling systems such as freezers, refrigerators, or air conditioning systems. Advanced models can include a filter to remove impurities and are capable of recycling the refrigerant for re-use. Another benefit of one of these machines is that they ensure that refrigerant is not accidentally released during servicing and repairs.
Specific units from Robinair are capable of oil-less refrigerant recovery.
This category contains HVAC equipment you won't find in any of the above categories. This includes A/C Superheat/Subcool System Analyzers, Heater Blankets, Charging Scales, Refrigerant Identifiers, Thermostats, and various HVAC Measurement Kits which can include a variety of HVAC tools bundled together for a reduced purchase price.
HVAC Resources
These links are excellent HVAC resources from TSI/Alnor. Click the images to download the PDF files.