01 / Start with your fluid and installation
For a quick local reading with control-room alarms, a magnetic gauge with switches or a transmitter is a useful starting point. To inspect color or a liquid interface, start with a transparent gauge. Pump start/stop control alone may only require point-level switches.
The table narrows the options; a fluid name alone does not select a model. Check composition, density at operating temperature, viscosity, crystallization, foam, solids and corrosion before confirming wetted materials and pressure/temperature configuration.
| Your application | Starting point and product | Reason / when to reconsider |
|---|---|---|
| Clean water / cooling-water tank | 562 / 563 / 564 magnetic | Clear local indication with optional alarms and transmission; compare 590 ultrasonic where side connections are unavailable or contact is undesirable. |
| Open pool / underground water tank | 730 submersible hydrostatic | No bypass chamber required. Density changes affect level conversion; check sediment, cable compatibility and the pressure-reference arrangement. |
| Clean oils / low-viscosity process liquids | 562 / 563 / 564 magnetic | Does not depend on conductivity. Low density requires a suitable float; a material change alone will not prevent wax, crystals or viscous deposits from restricting movement. |
| Acids / alkalis / corrosive chemicals | Plastic or lined magnetic chamber | Evaluate PP, PVC, PVDF or PTFE/PFA lining against composition, concentration, temperature and pressure. Polymer compatibility depends on the specific chemical and operating conditions. |
| Colour, turbidity or interface observation | 542 transparent | Provides a view of the liquid; opaque or fouling fluids can still prevent reading. Plan illumination and cleaning. |
| Water-level observation in steam equipment | 541 / 542 glass gauges | Check assembly ratings, glass protection and valves. Evaluate a 542 configuration where mica protection is needed; flange class alone does not rate the assembly. |
| Wastewater sump / pump switching | 506 cable float switch | Useful for point control; fibres and scum may entangle it. Allow travel space. Continuous measurement needs a separate hydrostatic or non-contact assessment. |
02 / Compare the trade-offs
| Type and product | Main benefit | Limits and maintenance |
|---|---|---|
| Magnetic / flag indicator | Passive local display; external flags do not contact the fluid; switching and transmission can be added. | Density-specific float selection; deposits or blocked bypass connections can cause sticking or a false reading. |
| 541 reflex | Bright/dark contrast suits clean liquids where actual color is unnecessary. | Not a reliable way to see actual color or a liquid-liquid interface; fouling reduces contrast. |
| 542 transparent | Allows fluid observation and, under suitable conditions, interface observation; mica protection can be evaluated. | Needs light transmission and suitable illumination; maintain both glass faces and their seals. |
| 590 ultrasonic | Non-contact option for suitable ambient open water tanks. | Foam, dense vapor, obstructions and turbulence can affect echoes. Allow the dead zone; sound cannot propagate through a vacuum. |
| 730 hydrostatic | Continuous monitoring in pools and deep tanks. | Conversion depends on density. Closed pressurized tanks need a separate treatment of gas-space pressure. |
| 520 float level switch | Point control with configured switching positions. | Contacts are not a continuous level value; check deposits, free travel and compatibility. |
| Radar (general comparison) | Non-contact radar does not rely on sound through a gas; it may be considered for vacuum or vapor service. | Dielectric properties, foam, obstructions and installation still matter. Talk to a specialist |
03 / Three conditions that change the selection
Low or changing density: select magnetic and float instruments using the minimum operating density. Recheck buoyancy when batches or temperature change. Hydrostatic conversion also needs the correct density.
Solidification, crystallization and deposits: assess heat tracing, bypass passages, drains and flushing. A jacket may help maintain fluidity but does not guarantee a clear chamber. If free float travel cannot be maintained, evaluate non-contact technologies.
Outdoor and extreme-temperature service: consider freezing, solar exposure, insulation and accessory ambient limits. Pressure/temperature suitability belongs to the complete chamber, float, glass, seal and valve configuration, not the strongest individual component.
04 / Check installation and service access
For side mounting, check connection centers, orientation, flange specification and the level span that must actually be visible. Visible length, measuring span, overall length and connection centers are different dimensions.
Allow lower clearance for float removal and draining, plus access to isolation valves. Top-mounted probes need withdrawal space. Ultrasonic installations must avoid inlet streams, agitators and wall echoes. A sketch and photos help more than an old model number alone.
Connect the task to the installation
01 Vessel · 02 Bypass chamber · V Visible range · C Connection centers
Local reading: check visible range, viewing distance and light, then compare indication types.
Choose a task to see what to confirm.
05 / Example: water and chemical tanks need different specifications
Water service tank: for a local reading and low-level pump stop, begin with 562 / 563 / 564 plus a 528 / 529 switch. If a control-room value is needed, check a compatible 531 transmitter. Provide the span, connection centers and actual pressure/temperature.
Chemical storage: also provide composition, concentration, cleaning fluids, operating temperature and density. Assess chamber, float and seals together. A stainless configuration selected for water is not automatically suitable for chemicals. These are selection examples, not claims of delivered installations.
For an inquiry, include fluid properties, minimum/normal/maximum operating and design conditions, span, vessel/connection drawing, display/alarm/4–20 mA requirements, power and environment. For incoming and outgoing quantities, continue to the flow-meter selection guide.
Explore related products and specifications
- 562 / 563 / 564 Series Magnetic Level Gauges →
- 541 Series Reflex and Transparent Glass Level Gauges →
- 590 Series Ultrasonic Level Transmitters →
- 730 Series Submersible Pressure and Level Transmitters →
- 520 Series Magnetic Float Level Switches →
- 506 Series Cable Float Level Switch Assemblies →
Product technical documents
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