MIXER SOURCE FOR MEDICAL SYNTHETIC-AIR DISTRIBUTION SYSTEMS, COMPLIANT WITH DIRECTIVES 93/42/EEC AND 2014/68/EU

INTRODUCTION

MIXTEL is a primary source of medical synthetic air available in different models according to the required flow rate: MIXTEL 30 – MIXTEL 60 – MIXTEL 120 – MIXTEL 200 – MIXTEL 500. MIXTEL consists of a mixer cabinet and a buffer tank. Both components are essential for achieving the intended purpose and, above all, for meeting the safety requirements of Medical Devices Directive 93/42/EEC. The system is the result of cooperation between two specialised companies that are leaders in Europe and worldwide: TGE s.r.l. – Techno Gas Equipment, which has many years of experience in the design and manufacture of mixing components and systems, and AMBRA Sistemi s.r.l., which has decades of experience in the design and manufacture of local and telemetry-based control systems for cryogenic gas installations. MIXTEL is intended to produce synthetic medical air by mixing pharmacopoeia-grade oxygen and nitrogen. This solution has become increasingly widespread in hospitals in recent years, for example:

• In intensive care for ventilatory support;
• For chronic respiratory failure, to provide respiratory support;
• In anaesthesia, as a carrier gas for volatile anaesthetics;
• In nebulisation therapy, as a carrier for pharmaceutical substances;
• In the management of immunocompromised patients, such as organ-transplant, cell-transplant or extensive-burn patients;
• In incubators, to supply controlled-quality air flows;
• For insufflation into body cavities.

Synthetic Medical Air, obtained by mixing the two primary gases nitrogen and oxygen, has chemical and physical characteristics that are undoubtedly superior to those of conventional Medical Air, which is produced directly from ambient air by compression and subsequent filtration. More specifically, Synthetic Air offers:

• High levels of purity due to the absence of harmful gases and contaminating chemicals such as lubricating oils
• Complete absence of bacteria, because the enclosed environment is difficult to access and unsuitable for bacterial settlement and reproduction.

Synthetic Air is produced directly at the end user’s premises by mixing systems installed in hospitals. These systems draw the primary gases from their respective cryogenic storage vessels and mix them in the correct proportions. The supply of Synthetic Medical Air therefore includes not only the primary gases, but also the mixing system and the associated management and maintenance service. Given the specific application and the high safety margins required, the service is normally carried out through the following operating procedures:

• Initial monitoring of the system until it is fully commissioned and optimised
• Scheduled preventive-maintenance and adjustment work
• Continuous monitoring of accidental events
• Rapid response to faults

The system was developed primarily to provide an efficient and complete solution for producing Synthetic Medical Air. It includes not only a technologically advanced mixing plant, but also a range of powerful tools to support the personnel responsible for operating and maintaining the system, all with low energy consumption. The scheduled maintenance specified by TGE s.r.l. is simple and intuitive and presents no particular difficulties. Another feature of the mixer is that the front panel can be customised with the customer’s logo. All materials used in its manufacture are exclusively of European origin. For complete system protection, both MIXTEL and the tank are equipped with a safety valve. These are, in brief, the main features that distinguish MIXTEL from conventional mixers.

BALANCED, PNEUMATICALLY OPERATED PRESSURE REGULATORS

COMPLIANT WITH DIRECTIVE 93/42/EEC AND CE-MARKED 0425 High mixture stability and maximum ease of use The heart of the mixing system is a high-precision, pneumatically operated dual balanced pressure regulator designed and manufactured by TGE s.r.l. It ensures repeatable mixture composition and long-term stability. This technology also greatly simplifies commissioning and adjustment, reducing these operations to the use of just two valves:

• the first sets the required flow rate by modulating the pressure downstream of the regulator
• the second corrects the percentage of oxygen in the mixture.

ZIRCONIUM-OXIDE ANALYSERS, KNUDSEN DIFFUSION EFFECT

Long service life and fewer periodic calibrations. The oxygen analysers, designed and manufactured by Ambra Sistemi s.r.l. specifically for this application, use a newly developed miniaturised zirconium-oxide cell based on current limitation in the diffusion region, known as the “Knudsen effect”.

MICROPROCESSOR CONTROL MODULE

High safety margins and new tools for technical personnel. The TA2000 microprocessor control module, developed specifically for this application by Ambra Sistemi s.r.l., manages the mixing process and supports a range of highly innovative functions. Its purpose is to ensure high safety margins while integrating and simplifying the work of operating and maintenance personnel. The Control Module therefore provides the following functions:

• Digital indication of operating parameters
• Programming of system parameters and alarm thresholds from the keypad and/or remotely via modem
• Local optical and audible indication, and remote indication, of alarm and shut-down states in compliance with the “Alarm signals for medical devices” standards
• Scheduled-maintenance overdue warning
• Remote viewing of current status and historical data
• Remote system reset
• Direct connection via an RS485 local network to other telematic equipment
• System consistency monitoring

SCHEDULED-MAINTENANCE OVERDUE WARNING

Automatic planning of scheduled work The TA2000 Control Module provides four timers, programmable from 0 to 999 days and associated with different periodic maintenance tasks. When a timer expires, it generates a specific alarm state that is transmitted remotely via modem. By selecting the relevant programming option, the operator can decide whether timer alarms should also activate the local optical and audible signals.

REMOTE CONTROL

Complete visibility of the system from the office or from home. Remote monitoring and control are available for the central unit.

REMOTE TRANSMISSION

Alarm messages reach the maintenance personnel’s mobile phones. Remote-transmission functions require a central remote-control station comprising a personal computer, the CRIOSYSTEM software application and a PSTN/GSM telephone line connected to it. With this equipment, MIXTEL informs the central station in real time whenever alarms or shut-down events occur and whenever maintenance timers expire. The central station then immediately contacts the maintenance personnel on their mobile phones, communicating the identification details of the active alarms (type and place of origin) by synthesised voice message, SMS and email.

MIXTEL TECHNICAL SPECIFICATIONS

Power supply 220 Vac, 50/60 Hz, P max. 60 VA, fuse 0.5 A Visual indications Backlit display, 4 lines x 20 characters Medium-priority alarm: yellow LED, diameter 20 mm High-priority alarm: high-efficiency red LED, diameter 20 mm Audible alarm Adjustable-intensity speaker, max. 95 dB at 1 metre Monitored parameters O2 analysis, inlet and outlet pressure, production flow rate, valve faults, leaks, analysis inconsistency O2 and N2 inlet pressure range 12 … 20 bar Minimum IN/OUT pressure drop 4 bar Operating pressure range 7 … 9 bar Combined error of O2 analysers < ±1% O2 of full scale (25%) Long-term drift of O2 analysers < ±0.2% O2/year O2 analyser warm-up time 2 minutes Alarm output No. 1 relay contact, software-configurable as N.O. or N.C., Vmax. = 250 Vdc/Vac; Imax. = 100 mA Local network interface Bidirectional, galvanically isolated RS485 local network interface Optional communication boards Telephone modem for analogue PSTN line Operating temperature 0 … 45°C

Tank supplied with the system

Available in two versions:

• AISI 304 stainless steel – compliant with Directive 2014/68/EU and CE-marked 0497 (manufactured by TGE s.r.l.)
• Carbon steel – compliant with Directive 2014/68/EC

Certifications and reference standards

• Directive 93/42/EEC as a Class IIb medical device, notified body No. 0425.
• Directive 2014/68/EU as Group 1, Category IV pressure equipment, notified body No. 0497.
• UNI EN ISO 7396-1:2016 Medical gas pipeline systems – Part 1: Pipeline systems for compressed medical gases and vacuum.
• EN 61000-6-2:2005 Electromagnetic compatibility (EMC) – Part 6-2: Generic standards – Immunity standard for industrial environments.
• EN 61000-6-3:2007+A1:2011 Electromagnetic compatibility (EMC) – Generic standards – Emission standard for residential, commercial and light-industrial environments.
• UNI EN standards