The Hydramotion XL7 is a high-performance viscometer which outputs measured viscosity in both analogue and digital formats.
The orientation-independent sensor has a solid construction with no moving parts, seals or bearings and consequently routine maintenance is not required. The device is factory-calibrated and shipped ready for immediate use, enabling viscosity measurement to begin immediately following installation and electrical hook-up.
The XL7 measures viscosity every second with high sensitivity and excellent repeatability. The instrument also calculates viscosity corrected to a reference temperature from a suitable temperature source.
All the necessary functions to derive real-time viscosity are performed by the sensor and its integral electronics. The Signal Processor supplied with the instrument allows the user to view all measured and calculated variables and configure the system for optimum performance.
1.1 Operating Principal
The sensor element consists of a resonant structure with an end mass or “bob”, which is made to vibrate resonate) at its natural frequency. When vibrating, the bob shears through the fluid. As this shearing takes place, energy is lost to the drag forces on the bob surface caused by the viscosity of the fluid. The on- board microprocessor measures the loss of energy in each cycle of vibration and uses the data to determine the actual viscosity of the fluid.
The XL7 is in a class of instruments sometimes called “resonant” or “vibrational” viscometers. The response of these devices is a product of viscosity and density, i.e. viscosity × density. In practice, however, density usually changes on a far smaller scale than viscosity and therefore has a negligible bearing on repeatability. If required, the correct fluid density can be entered via the Signal Processor.
1.2 Key Features
The XL7 viscometer is designed to withstand the rigours of continuous on-line viscosity measurement in a true operational environment. There are no moving parts, seals or bearings that can wear out or fail in service, giving high tolerance to harsh process conditions for long periods with minimal maintenance.
High accuracy and repeatability are achieved by the use of high-stability materials and a patented tuned resonance technology which exclusively measures shear viscosity. Amongst the many benefits of the technique is the natural rejection of plant vibration and the elimination of the effects of temperature, flow, entrained debris, bubbles or installation environment often associated with other types of on-line sensor.
With a compact, all-welded construction, the XL7 is completely self-contained and requires no ancillary pipework or equipment. High- temperature models require no special cooling and are installed in exactly the same way as standard sensors.
All Hydramotion viscometers are factory-calibrated using certified traceable viscosity standards and are shipped ready for immediate use. Installation and hook-up are simple and straightforward. Following proper installation, the XL7 should provide long, reliable and trouble-free service.
1.3 Range
- The XL7 viscometer is used in a wide variety of applications in every kind of process across manufacturing industry. Transducers are available with a full range of process fitting, material and finish options. By a suitable selection of standard and/or optional features it is possible to provide an off-the-shelf solution to a wide variety of process applications.
- Details specific to a non-standard instrument will be given in a Supplement to this User Manual.
- Standard models cover the following viscosity ranges:
| non-intrinsically safe* | intrinsically safe* | minimum range † |
| 100 | 150 | 0 - 1,000 cP |
| 101 | 151 | 0 - 5,000 cP |
| 102 | 152 | 0 - 10,000 cP |
| 103 | 153 | 0 - 50,000 cP |
| 104 | 154 | 0 - 500,000 cP |
| 105 | 155 | 0 - 1,000,000 cP |
† These ranges are indicative and relate only to Newtonian fluids.
* Intrinsically safe (“I.S.”) models are certified for use in potentially explosive atmospheres, as detailed in Section 3, Section 4 and Section 6. Non-I.S. models are for Safe Area installation only.
- The high-temperature HT2 models are available in all viscosity ranges for continuous use at temperatures up to 400°C.
- Instruments are fully identified by a Product Code composed as follows:
- Further codes may be added, depending on specification. For example:
| Code | Significance |
| IEC1 | safety certification type |
| TT | integrated temperature sensor (fitted in sensing bob) |
| Exxx | “extension” (length of shaft, from base of fitting to tip of bob) |
- The product label affixed to the transducer generally shows a shortened form of the Product Code, e.g. “XL7-100”, “XL7-153”, etc.
1.4 Calibration Certificate
- A Certificate of Calibration and Conformity is included with each instrument.
- Carefully verify the details shown on the Certificate, particularly as regards suitability for Hazardous or Safe Area use.
- The Certificate typically contains the following information:
| Item | Content | Example |
| Serial No. | Transducer serial number | XL7-1207-8743 |
| Certificate No. | Calibration Certificate number | 40969XL712078743 |
| Order No. | Customer’s Purchase Order number | 11935 |
| Product Code | Short form of Product Code shown on label affixed to transducer | XL7-150 |
| Customer | Customer name | XYZ Co., Inc. |
| Product Part Ref | Hydramotion internal reference | XL7-C-IEC1.HT2.M4 |
| Product | Product details (includes complete Product Code and description of transducer, plus safety certification where applicable) | Model: XL7-150-HT2-IEC1-d24-M4 XL7 Series Intrinsically Safe High Temperature Process Viscometer (etc.) |
| Additional Product Data | Wetted parts materials | 316 |
| Finish and/or surface coating | Std 0.8 micron AA Grade N6 | |
| Design pressure rating (bar) | 10 | |
| Process fitting type | 2" ANSI 150 RF flange | |
| Calibration Constants | Transducer-specific data Basis of calculation |
P30 -3.36794783E+00 (etc.) |