Rheonics Support

What products are involved?
SRV and SRD sensors.

What is the purpose of this article?
Show guidelines on how to use the Rheonics SR- Type sensors in laboratory setups using ovens, controlled heaters, or optical tables, usually to measure small sample static fluids. Rheonics accessories are discussed that are often used for table top measurements as well as for calibration verifications with reference fluids like NIST traceable viscosity and density references.

Oven-based sample measurement

Rheonics viscometer SRV and density and viscosity meter SRD are mostly installed inline for monitoring and controlling industrial processes. However. they can also be used in laboratory setups with static or moving fluid. This is common in the following cases: 

Early laboratory tests before inline installation in process line or tank: The user should be aware that if the fluid is non-Newtonian, the viscosity measured in static conditions will most likely differ from the readings when the fluid is flowing in the line. Density, on the other hand, would be the same.

Calibration checks: The Rheonics sensors are factory calibrated. Most quality systems require validating the calibration periodically. In those cases, NIST-calibrated fluids should be used. Refer to this article for more information and guidelines: Calibration verification procedure for inline viscometer and density meter 

Laboratory use of the sensor: Rheonics sensors can be used in laboratory environments. Rheonics accessories make table top setting easier for the SRV and SRD sensor. However, often table top measurements are seen as a way to compare against lab instruments, some considerations should be taken. Most lab viscometers operate at different shear rates and the viscosity for non-Newtonian fluids (majority of fluids around us) is shear dependent, so comparing measurements from different instruments require some idea about the flow curve, and mapping the measurements from instruments on the appropriate section of the flow curve.

Installation requirements

The type-SR sensors have a sensing element that requires minimum fluid volume (cross-section) to be maintained as shown in the next image.

Figure 1: SRV and SRD sensing areas.

The SRD has an additional requirement relevant to temperature differences greater than 20°C between ambient (sensor probe’s back) and fluid. This article explains the topic in detail. This scenario affects the density readings with a systematic offset. The solution is using a long insertion probe or a controlled temperature environment (for the SRD short or flush probes). This last option is more feasible in laboratory setups.

Rheonics offers accessories to use the SR-Type sensors (SRV and SRD) in laboratory setups.

Despite the recommended setup shown in this article, other laboratory installations can be used. Rheonics offers the STCM system for static or flowing fluids under controlled temperature conditions. Alternatively, clients can use proper setups for their case, following the recommendation made in proper installation of SRV and SRD. Next image shows general recommendations for laboratory setups.

General considerations for viscometer SRV measurements in laboratory, static or calibration setup.

Figure 2: SRV Laboratory Setup Guidelines

General considerations for density and viscosity meter SRD measurements in laboratory, static or calibration setup.

Figure 3: SRD Laboratory Setup Guidelines

Read more about SRD’s thermal equilibrium requirement. 
Review the calibration guidelines article for SRV and SRD.

Rheonics Sensor Probe Stand 

SCS-00A-ME: Stainless Steel Probe Stand 

This accessory is made of stainless steel 304 (1.4301), it is an bespoke, robust but light,  and high temperature capable stand to firmly hold the sensor probe upwards. 

Figure 4: Rheonics Stainless Steel Probe Stand 

SCS-00A-PM: POM Plastic Probe Stand

This stand is made of POM (Polyoxymethylene) a high mechanical strength plastic that ensures rigidity in the probe stand. It is recommended for application of up to 65°C only.

Both sensor probe stands, in any material, are the same for both SRV and SRD, hygienic and standard design, EX and EHEDG certified, and all X variants - except the Reactor probe (X7) and slimline probes (X6).

Figure 5: Rheonics POM Plastic Probe Stand

Table 1: Rheonics Probe Stand Setup Example

Rheonics Calibration Cylinders - SCC and HCC

These accessory are made of PTFE and are specially designed for the SRV, SRD, SRV-HS or SRD-HS (HS: Hygienic design). Due to the SRV’s sensing area being smaller than the SRD’s, the SRD cylinders can be used for the SRV as well, but not vicerversa.

All calibration cylinders are listed in next table, they all have a minimum liquid volume required and a maximum allowed, and O-ring required to ensure a leak-free seal. The sensor probe is mounted as shown in the example below.

Figure 6: Rheonics Calibration Cylinder

Table 2: Rheonics Calibration Cylinders

Calibration setup

Using Rheonics probe stand (SCS-00A-ME) and calibration cylinder (SCC-SRX), the user can create an ideal setup for laboratory uses with static fluid. 

The probe stand has holes at the base that can be threaded in tables to avoid unwanted movements.

Figure 7: Calibration stand setup in optical table

Table 3: Laboratory Calibration Setup Example

The setup can be placed in an oven to create a temperature-controlled environment for the measurements.

This is especially convenient for the SRD, to keep the thermal balance needed along its resonator and ensure the accuracy in density readings when fluid measurements above or below ambient temperature is required.

Figure 8: Calibration stand setup in oven

References

[1]: Calibration verification procedure for inline viscometer and density meter 

[2]: Ensure thermal balance in SRD resonator for density accuracy