What products are involved?
SRD Inline density and viscosity meter.
What is the purpose of this article?
To provide an overview of the SRD-X5 long insertion probe version and the installation options.

1. Introduction

The long insertion sensor (FPC) version is available for both SRD and SRV sensors. It is a sensor variant customizable in length and process connection, that gives full flexibility in mounting. Insertion length is a configurable parameter that is specified as "A" that can be requested from 100mm (for the SRD) up to any length needed by the client.

It is also available with any flange or process adapter, as long as the process connection requested is 316L or 304L and has an ID larger than Ø33 mm.

The client should then state the "A" length and process connection norm, which has the letter code “B”. The typical lead time is 6-12 weeks for these customizable probes. Lead times can change and will be confirmed by sales in the order confirmation.

Figure 1: SRD-X5 reference drawing.

Figure 2: SRD-X5 possible configurations.

Order code
Insertion length A
Connection type B
Customizable ID>33mm
Drawing and CAD file eg. for flangehttps://rheonics.com/srd-long-flange/

With a customizable insertion depth there are many installation advantages. The SRD-X5 sensor is recommended for following scenarios:

  • Installation with long standpipes
  • Mounting in tank’s lid
  • Jacketed walls in tanks or reactors
  • Elbow and cross-pipe installations
  • Most flange installations
  • Fluids with yield stress
  • To ensure good accuracy when fluid temperature is at much higher or lower temperature than ambient temperature

2. Installation examples

2.1. Long insertion sensor in tee or long standpipe

This is a typical method of process installation. Also, this type of process installation allows using already existing flanges on a process line. The recommended insertion depth “A” should be such that the sensing area is fully exposed to the flow. It is good practice to also have the 14 mm neck diameter exposed to the flow, as indicated by the figure below.

For an inline pipe installation of the SRD, it is recommended that the sensor’s tip has a parallel orientation with the flow. Follow this article for more information: SRD fluid end orientation.

Figure 3: SRD-X5 Tee Installation

2.2 Long insertion sensor in Elbow or Cross pipe

The preferred installation scenario is installing the SRD long insertion probe in a T-piece, such that the flow is parallel to the sensing element, like in an elbow.

This installation method is ideal for a reliable density and viscosity measurements with the long insertion probe, even for highly non-Newtonian fluids and fluids with yield stress. This also helps with considerable thermal differences between the fluid and ambient (sensor back). The insertion depth “A” should be sufficiently long, that the Ø14mm section is in the straight section of the T-piece (blue rectangle).

Inserting the sensor further into the flow, benefits the measurements, but may increase the pressure drop due to the reduced cross-sectional area.

Ideally, the flow should go towards the sensor for maximal exposure, the inverse flow direction may affect the response time of the sensor. In next installation examples, the fluid flows against the sensor, hitting the sensor tip first. 

Figure 4: SRD-X5 on Elbow Installation.

Figure 5: SRD-X5-NPT 1.25” in Jacketed Pipe

Figure 6: SRD-X5-NPT 1.25” Elbow Installation

2.3 Long insertion sensor in tank’s roof

There are cases where the client needs to install the sensor in a tank or reactor, and a wall or bottom installation is not possible due to jacketed walls, scrapper or mixing blades near the wall, etc. Then, an installation from the tank's top or lid is the best solution.

The SRD long insertion probes are typically used when an installion of the sensor from the top is needed. It is recommended that the entire sensing element is fully wetted at all times when a measurement is needed. The filling height may vary over the course of the reaction, and be dependent on how much of each component has been added, or if there is a constant influx of air.

This installation option is well-suited for next scenarios:

  • There is no clearance between the sidewall and the blade (scrapper blade often is quite close to the wall)
  • There is no existing port on side wall or bottom of reactor vessel and installing a new port is not possible
  • There are existing ports on the lid or are easier to install
  • Vessel is double jacketed which makes it hard to install ports

Figure 7: SRD-X5 on Tank’s roof

Alternatively, another solution for installation in tanks is the use of the TMA-34N accessory, read more about this here.

3. Adjustable Process Connector - APC

Rheonics SRD-X5 sensor can be installed with the APC adapter for ambient pressure. The APC is a mechanical joint of pieces that can clamp a flange or process connection on the sensor body without welding. This enables easy change of flanges and the inmersion depth can be varied.

The APC can adjust a Tri-Clamp, flange or any other connection with a maximum thickness of 1” and an OD diameter of at least 50mm.

Figure 8: Rheonics SRD-X5 with APC adapter.

Figure 9: Rheonics SRD-X5 with APC drawing.


[1]: https://rheonics.com/products/inline-density-meter-srd/

[2]: https://rheonics.com/tma-34n/