Testing, Surveys and Support Services

Premier Security Ballistic & Blast Ltd provides surveys, testing and commissioning services across the specialist shielding disciplines, from pre-construction site surveys through to witnessed acceptance testing of the completed installation.

Shielding, containment and speech privacy have one characteristic in common that separates them from most of construction: none of them can be assessed by looking at the finished work. A shielded room that leaks at 20 dB looks identical to one performing at 100 dB. A gas tight door that has lost its seal compression looks exactly like one that has not. A masking system that has never been tuned looks like a ceiling full of emitters.

Performance in these disciplines is a measured property or it is an assumption. The purpose of this part of our offering is to replace the assumption with a number.

Surveys and Pre-Installation Studies

Most of the expensive problems in a shielding project are decided before anything is built, which makes survey work the highest value stage of the whole process.

Electromagnetic Field Surveys

Where a project has no defined attenuation specification, and most do not, a site survey quantifies the background field strengths actually present. From that baseline a realistic and testable attenuation target can be written. Specifying a figure without the baseline tends to produce either an underperforming shield or one that costs substantially more than the requirement warranted.

Pre-Installation Studies on EMF Effects

Assessment of how electromagnetic fields present at a site will affect the intended use of a space, and what would need to change for the intended use to be viable. This is the study that determines whether a proposed location is suitable at all, which is a considerably cheaper question to answer early.

MRI Vibration and Magnetic Field Fluctuation Surveys

Two site conditions can render an MRI installation unusable regardless of shield performance. Mechanical vibration transmitted through the structure degrades image quality, and time varying magnetic field disturbance from moving ferrous masses such as vehicles, lifts and trolleys affects image stability. Scanner manufacturers publish limits for both. We survey against those limits before construction, when remedial options are still broad.

Design Phase Input

Technical input during the preliminary shielding design phase, before construction detailing is fixed. Shielding affects structural setting out, mechanical and electrical routing, door schedules and the acceptance programme, and every one of those is cheaper to influence than to correct.

Shielding Effectiveness Testing

Shielding effectiveness testing measures the attenuation actually achieved by a completed facility, across the frequency range specified, against a defined pass criterion at each band.

Testing is carried out on completion to demonstrate conformance with the original specification. Where a facility is being assessed rather than handed over, the same methods establish current performance against the level it was originally designed to achieve.

Pulse Injection Testing of EMP Filters

Filters on power and data lines crossing a shield boundary are the components most likely to be assumed rather than verified. Pulse injection testing subjects the filter to a representative transient and measures what passes through it, to applicable NATO military standards.

This matters because a filter is the one part of an EMP protected envelope whose failure is entirely invisible. A degraded gasket can be inspected. A filter that no longer attenuates looks exactly like one that does.

Gas Tight Door Pressure Testing

Where the air permeability of a gas tight doorset needs to be established, we carry out pressure testing under controlled conditions.

The doorset is mounted to our test chamber and pressurised using an air compressor capable of applying a controlled test pressure continuously for one hour. On completion of pressurisation the door and chamber are isolated from the pumping system and left connected to an airflow meter, and leakage is measured over a further hour. Both positive and negative pressure conditions are tested.

Tests are generally performed to the relevant European air permeability test method for windows and doors, and we can work to customer specific requirements where a project or a regulator demands a different protocol. We can also advise on which test method is appropriate for a given requirement, which is often the more useful conversation.

Data Centre Testing

Data centres are assessed rigorously on security, availability and standards compliance, and rarely on electromagnetic exposure. We provide testing services to identify weaknesses in existing host rooms and buildings, covering both conducted and radiated paths.

The relevant threats are electromagnetic pulse and Intentional Electromagnetic Interference, the latter generated by non-nuclear devices such as a Marx generator. Both can disrupt or destroy processing and storage hardware, and neither is addressed by any measure appearing on a conventional data centre resilience assessment.

Sound Masking Tuning and Verification

A masking system is not complete when the emitters are installed. Every system is tuned in accordance with the manufacturer's guidelines and then verified using sound control test equipment, to confirm that the intended masking level and spectrum have been achieved uniformly across the treated area.

Uniformity is the measure that matters. Occupants notice variation far more readily than they notice level, and almost every complaint about a masking system traces back to either uneven coverage or an installation that was never tuned at all.

Remedial Assessment of Existing Installations

Where an existing shielded facility is underperforming, or where performance has never been established, we can assess current condition and propose remedial action.

• Measurement of current shielding effectiveness against the original design intent
• Identification of the specific apertures or components responsible for the shortfall
• Proposed remedial actions, scoped and prioritised by their effect on measured performance
• Retesting following remedial works to confirm the improvement achieved

Degradation in shielded facilities is rarely uniform. It is usually concentrated in a small number of apertures, most often door contact systems that have worn, gaskets that have compressed permanently, or penetrations added after handover without treatment. Finding which ones is the whole exercise.

Writing Testing Into the Specification

The most common reason a shielding project fails to demonstrate its performance is not technical. It is that nobody specified how performance would be demonstrated.

• State the required attenuation as a figure at each frequency band, not as a single headline number
• Name the test standard to be applied
• Make testing a witnessed acceptance activity rather than a contractor self certification exercise
• Define what happens if the facility does not pass, including who bears the cost of remedial work and retesting
• Establish the attenuation target from a survey where none has been set, rather than adopting a figure from an unrelated project
• Programme testing before the room is handed over to the equipment installer, not after

Testing and Support FAQs