In this chapter we will cover:
- How to select the right installation point for your flow meter: what to take into account and what to avoid.
|The installation point is crucial for correct measurements! To ensure the highest possible measurement accuracy: follow this chapter carefully!|
|These devices are for use with Air, Nitrogen, Argon, Helium, Carbon Dioxide and other non-hazardous and non-corrosive gases.|
2. Take into account
2.1 Instrument specifications
Stay within the specification of the specific flow meter (Chapter J). These include, but are not limited to:
- The type of gas
- Range of the flow, pressure and/or temperature
Note that the basic specifications can be found on the sticker on your flow meter. For all specifications, check the product datasheet.
- For wiring.
- For maintenance: at least once a year be able to handle the device either directly or e.g. by use of scaffolding.
2.3 VPFlowScope technology and locations
The key to the proper installation of your VPFlowScope is selecting the right location for the installation. Always check the measurement principle of your flow meter and the associated air conditions.
|Type||Description and location|
|VPFlowScope DP||Differential pressure technology. Meant for installation before the dryer in saturated, hot air conditions with relatively high flows.|
M / Probe / In-line
|Thermal mass flow sensor. Install in clean, dry air only. Installation after the dryer. The sensor will damage when being installed in wet air conditions.|
2.4 VPFlowScope DP location
|The VPFlowScope DP is a compressed air flow meter, not a water meter. A location that could hold water, should be avoided in all cases!|
|During the installation of VPFlowScopes the up- and downstream lengths have to respected by the pipeline table, which can be found in the following chapter: D1.2.5 Stable gas flow profile.|
2.5 Stable gas flow profile
Any obstacle in the pipeline like an elbow or diameter change will result in non-stable flow and thus incorrect measurements.
An example is a double elbow and gas profile. In this case, stable at a length: 30 * pipe diameter.
Please follow the piping table as a practical guideline. These are minimum industry recommended lengths. If you have more length available, please use it, this will always lead to better results. Also be aware that any upstream or downstream objects, for example, other insertion probes may affect the measurement results.
D = inner pipe diameter
|Picture||Description||Effect||Minimum upstream length||Minimum downstream length|
|Single elbow||Distorted flow profile||30 * D||10 * D|
|Complex feed-in situation (header)||Distorted flow profile||40 * D||10 * D|
|Double elbow, multiple elbows following each other||Distorted flow profile + swirl||40 * D||10 * D|
|Pipe diameter change.|
Small –> large
Gradual or instant
|Jet shaped flow||40 * D||5 * D|
|Pipe diameter change.|
Large –> small
Gradual: 5° to 7°
|Flattened flow profile||10 * D||5 * D|
|Practical situations can have multiple sources of distortion. The guidelines are practical, not science. VPInstruments does not take any responsibility for the correctness.|
3. Avoid the following
|1. Mechanical stress on the flow meter: this might damage the entire flow meter.|
|2. Excessive heat. This can damage the sensor. Check temperature specifications.|
|3. Corrosive atmosphere. This can damage the sensor’s housing over time.|
|4. Electrical problems: high voltage / high power.|
|5. Mechanical Vibrations. These can lead to damage over a longer period of time.|
|6. The danger for damage e.g. walking bridges of forklift trucks passing by.|
|7. Water exposure VPFlowscopes are rated IP65, they are only splash prove. Potential water damage on the outside, avoid areas of high humidity and avoid dripping.|
|8. Any environmental source that can cause a potential error.|
4. Next Step
Now that you know what to take into account when positioning the VPFlowScope it is important to know how to do it with the right specification of your insertion flow meter.
Next Step: D2. Insertion point for insertion flow meters and how to hot tap one.