What products are involved?
SRV - Inline Viscosity Meter
What is the purpose of this article?
To give guidance on the installation of a G1/2” SRV sensor (SRV-X1-12G).
1. IntroductionSRV is Rheonics sensor for inline viscosity measurement (viscometer). Read more on SRV here.
The industrial G connection is a cylindrical thread connection that follows the norm ISO 228. It is also referred to as BSPP (British Standard Pipe Parallel).
Rheonics SRV with G1/2” thread connection has the order code SRV-X1-12G. It is categorized as a small probe and it is designed with a groove for an O-Ring of Ø22x1.5 mm. This O-Ring is required for certain installations, but not all, as explained in this article. This sensor probe variant has different accessories available such as a flow-through cell and weldolets (useful for flush hygienic installations). Rheonics offers the O-Ring in FKM as standard material.
| Note: The original version of the SRV-X1-12G did not have the groove for the O-Ring. Aside from this feature, all other specifications are the same. |
Figure 1: SRV G1/2” dimensions
Specifications | |
Sensor | |
Order code | SRV-X1-12G |
Connection type | G 1/2" |
Drawing file | |
ZIP CAD file | |
2. General installation guidelinesSR-sensors can be placed at any point in a process and at any orientation as long as the next considerations are followed to ensure stable, accurate, low-noise measurements.
2.1 Submersion
The SRV has a sensing element shown inside the red section (sensing area) in Figure 2. This section of the sensor should always be fully submerged in the fluid since SRV measures what is in contact with its sensing element. Ensure this area is unobstructed by external objects.
Figure 2: SRV-X1-12G sensing area
2.2 Stagnation/dead zone
Avoid dead or stagnant zones around the sensing area (Figure 2). Dead zones are defined as any space, inside the red zone, where fluid transport is insufficient leading to immobile/static fluid, as well as possible accumulation of solids and deposits, or unwanted material like air. These all have negative effects on the measurement.
A clearance of at least 5mm is recommended between the SRV sensor tip and a pipe wall or any other obstruction.
2.3 Orientation independence
SRV has a symmetrical tip, making it possible to face a flowing fluid in any direction. Its shape enables the fluid to be in contact with the tip without creating recirculation zones.
Figure 3: SRV sensing tip.
2.4 Flow
For Newtonian fluids flow rate does not affect the viscosity, so SRV should measure the same values in static and moving states of a fluid. For non-Newtonian fluids, the flow rate does matter and viscosity readings may differ between static and moving conditions. For processes with non-constant flow rates, the recommendation is to install the SRV in a section in the pipeline with the most consistent flow rate to have a steady viscosity value.
| Note: Rheonics SRV operates with static and flowing fluids. If the fluid is non-Newtonian, a viscosity difference will likely be observed between states and if fluid speed varies, however this is totally dependent on the fluid's properties. Check this article to veriy the fluid velocity limit for the SRV: SR probes for highly viscous fluids and high fluid speeds. |
Flow rate is also relevant to ensure the full submersion of the SRV sensing element into the fluid. For a process with a low flow rate, pipes may not be full of fluid at all points, so SRV should then be placed in a section where the pipe is usually full of fluid (i.e. after a pump). Installing the sensor upwards can solve the issue of non-full pipes but should not be considered for fluids with solids or characteristics that can create deposits around the sensing element.
In all cases, the SRV’s sensing element should be submerged in the fluid in motion. It’s best to avoid installations with long standpipes (i.e. using a long weldolet or tee), since that may lead to not good fluid transfer resulting in measurements that do not reflect the true state of fluid or worse high noise measurements.
Figure 4: SRV-X1-12G installation indications
3. Installation optionsAs explained in this section, the use of an O-Ring for the SRV-X1-12G is not always required. When the O-Ring is used, its size will vary depending on where it is placed.
3.1. G1/2" Weldolets - HAW accessories
The HAW line of Rheonics weldolets enable the installation of the SRV-12G in tanks and pipes (also suitable for the SRD Density and Viscosity Sensor). These weldolets have two versions, one with metal-metal sealing (no O-Ring required) and another with an O-Ring Ø15.1×1.6 mm sealing for hygienic installations. For the latter, follow the accessory page instructions of installation for details on O-Ring placement. Hygienic certification for the -OTK adapter is currently available with 3-A, while EHEDG certification is planned.
- HAW-12G-MTK: Weldolet with metal-metal seal
- HAW-12G-OTK: Weldolet with a Ø15.1×1.6 mm O-ring seal
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Figure 5: HAW-12G-MTK | Figure 6: HAW-12G-OTK |
3.2. Threaded port on pipe or tank wall
Sensor probe installation is also possible by creating a threaded hole in the pipe or tank.
O-Ring at conical surface
Placing an O-Ring at the conical surface of the probe ensures that not even in case of a thread sealing failure, can the process fluids come in contact with the threads of the probe. This is especially required for hygienic application. The O-Ring size is Ø15.1×1.6 mm. Correct machining of the sealing interface is key, so user should follow Rheonics instructions as detailed here: Compression sealing using SR X1-12G interface.
O-Ring at probe's groove
This installation requires a Ø22x1.5 mm O-Ring to be placed in the probe's groove above the G1/2" thread. For this installation client can create a bore through G1/2" thread in the installation point or use a conical sealing following instructions here: Compression sealing using SR X1-12G interface.
3.3 Flow-through cell HPT-12G
Rheonics accessory HPT-12G is recommended for an inline installation of the SRV G1/2” in high pressure aplications, especially in small line pipes. Visit its accessory page here.
This accessory requires the use of a different O-ring, also supplied by Rheonics, with a dimension of Ø15.1 x 1.6 mm. This flow cell withstands high-pressure conditions (up to 500 bar) and ensures no dead zones around the sensor. Due to its G1/2” inlet and outlet ports, it can be used for small lines (e.g. DN20).
Steps for flow-cell installation:
i. Pleace the Ø15.1 x 1.6 mm O-ring in the notch of the flow cell, right after the conical section.
ii. Place the sensor in the flow cell and thread it in completely.
iii. Connect the flow cell to the line, possible connectors adaptors are HF/60-SWOS-12-DN12.
Figure 7: SRV in HPT-12G flow cell.
| Note: Recommended torque for threading is 18 N.m. However, installation of the SRV-X1-12G can generally be done by hand, as manual tight is enough to ensure a correct sealing. |
Referenceshttps://rheonics.com/products/inline-viscometer-srv/