The SPTMAN by JF Strainstall is an easy to use and portable system that is used to calculate hammer energy.
The SPTMAN system measures the actual energy transferred from the drive hammer to the drive rods and calculates the hammer energy coefficient by comparison with the theoretical potential energy.
The heart of the system is a rugged, portable analyser with solid state memory. The system is supplied with a standard 54mm diameter instrumented SPT rod, as well as a waterproof carry case for added protection.
Tests are carried out using as easy to follow menu display which enables hammer energy and energy ration to be displayed in real-time.
System service and calibration
The measurement of SPT hammer energy is now recommended for all Standard Penetrometer Test (SPT) systems.
BS EN ISO 22476-3 states that the hammer energy ratio has to be known and have a certificate of calibration available if N values are going to be used for the quantitative evaluation of foundations or for the comparison of results.
This standard also recommends that checks should be carried out on a six monthly basis. JF Strainstall recommends that it is also good practice to carry out a calibration at the start of any large contract.
Benefits of the SPTMAN hammer energy tester:
- Instant hammer energy measurement and transfer coefficient calculation
- Rugged and lightweight system
- Storage for over 700 results
- Complies with the relevant parts of both BS EN ISO 22476-3 and ASTM D 4633-10
- Backlit LCD screen for working in dark environments
- JF Strainstall's calibration service available
The SPTMAN analysis software is supplied as standard, and adapts a user friendly, Windows based platform for downloading data, analysing results and producing calibration certificates.
The certificate includes plots of force, velocity, acceleration and displacement; as well as measured energy, theoretical energy and energy ratio. Full details of the rig and site can also be shown.
The SPT hammer energy measurement method is based on the propagation of waves in long elastic cylinders. When the SPT rod is struck with a falling weight, the rod section is deformed (enlarged) and this enlargement travels down the pile to the base of the rod where it is reflected back.
The force transmitted to the rods is calculated by measuring the axial strain in the rod over a period of time and taking the modulus and cross section of the rod into account by:
F(t) = Aa x Ea x εm(t)
The particle velocity of the measurement section is determined by integrating data from the accelerometers over a period of time. The energy which passes into the drive rods can be determined from the force and velocity data using:
E(t') = t∫0 F (t) v (t) dt
SPT hammer calibration service
JF Strainstall offers SPT hammer calibration services whether on-site or at one of our specialist testing facilities located in the UK and Ireland.
It is recommended that SPT hammers are calibrated at 4 monthly intervals to ensure efficiency and comply with the latest EN Eurocode specifications.
JFTS' SPT hammer calibration service uses the latest SPTMAN system, designed specifically for SPT hammer energy measurements. We carry a range of adaptors to suit a variety of hammer threads and all of our equipment is fully calibrated to national standards ensuring high accuracy.
Calibration's can be completed at our specialist testing facilities and are fully compliant with BS EN ISO 22476-3 and ASTN D 4633-05. We provide free stamping to uniquely mark your hammers and certificates are available on the same day.
We also provide on-site testing services as well as equipment and training support, should you decide that you want to do your own testing.