DJB Instruments (UK) Ltd products

The A/28/E is the world’s smallest piezoelectric fully welded stainless steel accelerometer. This ultra-miniature piezoelectric vibration transducer provides virtual transparency when applied to the lightweight structures, allied to relative freedom from strain induced error. A/28/E incorporates a mechanically pre-loaded shear plate sensing element. Good practice in use of A/28/E will maximize service life. Removal from a structure involves shearing an adhesive bond, shock means are not advisable, use the detachment tool provided. Abrasive cleaning of the attachment face will reduce base thickness over time; sparing use of adhesive will aid longevity and data accuracy. 0.4pC/g nom., 0.19gm, -50°C to 200°C Max Temp.

Sub-miniature, all welded, Konic shear sensing element based vibration transducer. The low mass of the A/25/E renders its transparent in the vast majority of light weight structure vibration measurement applications. The A/25/E is adhesive mounted. A detachment tool is provided to shear adhesive joints. Shock removal is to be avoided as being deleterious to the integrity of the transducer. Abrasive cleaning of the attachment face will reduce base thickness over time; sparing use of adhesive will aid longevity and data accuracy. Signal outlet is via a surface contact socket. Mating connector preload torque should be 7cNm, the locknut tightened to 12cNm for signal integrity to 10,000g. Insufficient preload may result in intermittent signal loss.

The A/24/E range of accelerometers are miniature adhesive/stud mount PE charge output accelerometers, offering a small size and low mass of just 2grams. Using DJB’s unique Konic shear® ceramic design offering superior cross axis control and performance, the low mass of the A/24 range minimizes mass loading effects in a wide range of vibration responses and structural testing applications. The adhesive base versions are available with and without ceramic isolation and the integral stud option provides mechanical fixing. All versions use the miniature coaxial KP connector. 5pC/g nom, 2gm, -55°C to 250°C Max Temp.

A generic range of lightweight, Konic shear® sensing element based vibration transducers offering a choice of tapped base stud mount or flat based adhesive attachment and each with side or top mounted connector. All welded construction maximizes temperature range and reliability. Adhesive mounted versions - Abrasive cleaning of the attachment face will reduce base thickness over time; sparing use of adhesive will aid longevity, whilst also maximizing data accuracy. The A/23 range is available with a wide range of mounting options. 8pC/g nom., 3.4-4.9gm, -55°C to 250°C Max Temp.

General purpose piezoelectric accelerometers well suited to a wide range of vibration analysis and shaker testing applications, particularly those requiring a higher operating temperature. Using the unique DJB Konic Shear® piezoelectric ceramic sensing element for superior performance and reduced long term cross axis error. The A/20 range offers a side entry or top entry tapped base model with an all welded titanium construction. In addition the TC version has a hermetically sealed top entry TNC connector. All versions have welded internal connections for a robust sensor suitable for many harsh environments. Relative freedom from strain induced error reduces low frequency measurement uncertainty. 30pC/g nom. 12.5-27gm. (-71°C opt) -55°C to 250°C Max Temp.

The Konic shear® sensing element of the A/22 incorporates a mechanically isolated central sleeve that comprises part of the transducer casing, thus providing an annular through hole for attachment.  The feature allows 360º connector orientations and minimizes height, thus facilitating installation. In addition all welded construction and total absence of epoxies maximizes reliability and temperature range.  The A/22 provides an output comparable that of the A/20, with the advantage of 50% reduced height and total freedom of cable orientation. 26pC/g nom. 12gm. -55°C to 250°C Max Temp.

The A/29 is a robust and highly sensitive lightweight accelerometer which is able to withstand high temperatures in excess of 250°C. This makes the A/29 is an ideal candidate for any application requiring high sensitivity measurements with very little margin for error. Close tolerance 100pC/g normalized output accelerometers with ultra low strain induced error. Piezo-electric materials convert mechanical loading, however induced, to electrical charge. The A/29 is specifically configured to minimize the effect of physical inputs other than acceleration, thus enhancing measurement integrity in situations where flexural strain of the transducer could give rise to significant errors. 100pC/g nom, 45-50gm, -50°C to 250°C Max Temp.

High output together with minimal susceptibility to strain induced error extends the measurement range of the A/21 down to the 10-5g, 10-1Hz region. The A/21 application area thus includes low level, low frequency dynamic analysis as occurs in the civil and marine engineering fields. The KONIC shear® sensing element, all welded construction, and total absence of epoxies and soldered connections maximises sensitivity /mass ratio (3pC/gm), reliability, and operating temperature. 360pC/g nom, 95-102gm, -50°C to 250°C Max Temp.

Ultra high output, multiple shear plate vibration transducer. Shear plate construction provides near total isolation from mechanical inputs other than acceleration, thus safe guarding measurement integrity in applications where vibration is accompanied by high dynamic strain levels. Generalizing, these conditions are prevalent where modal frequencies are low, and are thus associated with vibration surveys of large structures.  Transducers exhibiting significant strain response may operate more akin to strain gauges at low frequency excitation and their use is to be discouraged.  A number of parallel shear plates equivalent in total thickness to single plate of charge sensitivity Q and capacitance C, generates charge nQ. Clearly taken to the limit, noise degradation overrides signal increase, hence these products are largely a compromise between signal/noise and mass/size. This Accelerometer is also available as an IEPE version -A1600.

The A/800 is the highest sensitivity accelerometer in the DJB range. Using multiple shear plates and large masses the 9000pC/g sensitivity makes it perfectly suited to seismic surveys and other micro g level measurement – virtual immunity to strain input side effects provides guarantee of low frequency, measurement integrity. System noise level of 10-2pC is equivalent to 1mg. With bandwidth restricted to 1 kHz, noise floor should be significantly below this.