Můžeme použít pro rozvody vody, vytápění a plynu jakékoliv měděné trubky?

Ne, pro rozvody vody, vytápění a plynu můžeme použít pouze měděné trubky, vyrobené podle ČSN EN 1057. Z hlediska pevnosti a tvárnosti se prodávají jako měkké R220, polotvrdé (R250) a tvrdé (R290).

What makes a sprinkler head activate?

When the sprinkler head reaches a certain temperature it will activate.

Wozu gibt es Starkstromkabel?

Starkstromkabel aus Kupfer werden hauptsächlich für die Energieübertragung und -verteilung in Städten und Großbetrieben eingesetzt. Der Leiter besteht aus mehreren Einzeldrähten (Seelen), so dass das Kabel Bewegungen folgen kann. Starkstromkabel für feste Verlegung mit nur einem Draht pro Ader werden aus Kupfer bis höchstens 16mm² hergestellt. Bei Aluminium-Erdkabeln hingegen funktioniert die Aufteilung in mehrere Seelen nicht. Diese Kabel sind daher sehr steif, zumal die Leitfähigkeit des Aluminiums nur 1/3 derer des Kupfers beträgt, weswegen der Leiterquerschnitt 3/2 Mal so groß sein muss. Da Aluminium aber um 65% leichter ist als Kupfer, ist das Aluminiumkabel für Mittel- oder Niederspannung trotz größeren Durchmessers noch leichter. Für Hochspannungs-Erdkabel, sofern sie überhaupt zum Einsatz kommen, was aus physikalischen Gründen nur sehr begrenzt möglich ist, wird Kupfer bevorzugt, weil hier für relativ wenig Leiterquerschnitt relativ viel des ebenfalls teuren Isolierstoffs benötigt wird. Der größere Querschnitt des billigeren Aluminiums würde eine größere Isolierhülle erforderlich und damit das gesamte Kabel teurer machen.

Jak lze bronzová díla chránit proti korozi, pokud jsou umístěna venku?

Lze použít laky, leštění voskem, nebo obojí.

What manufacturing methods would be suitable for lock parts made in high tensile brass?

Either extrusion, if the shape is regular, or hot stamping for more complicated shapes.

Jak lze zabránit korozi nebo skvrnám na obráběných součástech z hliníkového bronzu během přepravy?

Klíčem je důkladně je vyčistit, odstranit vodu, chránit a udržovat je suché, takto:

  1. Po vyčištění je důkladně osušte pomocí odvodňovací tekutiny, jako je WD40.
  2. Odstraňte zbytky vody proudem teplého vzduchu.
  3. Pokryjte součást ochrannou vrstvou, jako je benzotriazolový inhibitor nebo blokový kopolymer.
  4. Zabalte do dřevěných bedýnek, vyložených papírem, nasyceným benzotriazolem. Lze také použít granule, absorbující vlhkost, aby vysušovaly vzduch uvnitř bedny. Po rozbalení odstraňte ochrannou vrstvu fosforečným roztokem a důkladně součást osušte.
My datacentre has a UPS. Is that enough protection?

How important is it that your data integrity is maintained and that your users have instant access to it?

A (static) UPS has a finite energy store so that, in the event of a supply failure it will provide power for a short time. This available time can be used in several ways depending on the needs of the organisation.

It can be used (and most frequently is used) to perform an orderly shut down of the network and servers. This protects transactions and ensures integrity of the data. However, once triggered, the process allows no new access to data – i.e., your users have no service. Service is only restored after the power supply has been re-established and the servers and network devices re-booted. If the operation is losing money by the minute, this is unlikely to be acceptable!

Another approach is to use the limited time available to start up an auxiliary generator to take over the supply from the UPS. This allows the operation to continue as if nothing had happened – assuming of course that the generator and fuel supply are properly maintained and work as expected.

Alternatively the time can be used to transfer transactions to another site, either an active peer site or a passive standby site. Again, as far as users are concerned, nothing has changed.

Whatever approach is taken it is most important that the standby power available is used carefully. Only essential equipment should be connected to the UPS system – servers, communications, network devices, essential PCs – no coffee machines, laser printers, etc.!

¿Cómo fuciona en la práctica la combinación de tubos de cobre con aletas de aluminio?

Los serpentines con tubos redondos de cobre y aletas de aluminio llevan muchos años siendo una combinación ganadora para los sistemas de aire acondicionado y refrigeración. Los fabricantes aprovechan las ventajas de montaje que les ofrecen estos componentes y a los técnicos les resulta sencillo unir y reparar las tuberías de cobre in situ. Y lo que es aún más importante, esta tecnología ampliamente implantada cuenta con una gran durabilidad probada en la práctica, lo que conlleva unos niveles más elevados de satisfacción del cliente.

Bestehen die 1-, 2- und 5-Euro-Cent-Münzen aus reinem Kupfer?

Nein, sie bestehen aus Stahl, der mit einem dünnen Kupferüberzug beschichtet wurde.

¿Por qué se utiliza el cobre y las aleaciones de cobre en la acuñación de monedas?

Desde la antigüedad, el cobre se ha utilizado para fabricar monedas; los romanos ya empleaban con regularidad el cobre para esta aplicación. Las razones para usar cobre son su excelente resistencia a la corrosión, la facilidad de estampación, su buena conductividad eléctrica para las máquinas expendedoras, sus propiedades antimicrobianas y la facilidad de reciclado.

A specification describes a brass as CDA 360. What is this?

This is an old CDA Inc (USA) spec—it is now UNS C36000. The UK equivalent is CW603N (CZ124) and is a free machining brass.

My process control system is not reliable and I suspect a voltage dip problem. Where do I start?

The steps in identifying the problem are:

Monitor at the supply to one or more of the affected devices. One problem is that the monitor threshold settings need to be set carefully so that all interesting events are captured, but the smaller, uninteresting events are not. This can take some trial and error to get right, but it improves the quality of data that you collect and is worthwhile. Alternatively, choose a tool that applies the thresholds retrospectively – these capture all the data, but let you choose what you view. Often, the simple transient capture functions found on hand-held power analysers are useful in the early stages – they are simple to use, the results are easy to interpret and they are easily moved around the installation.

Assuming that the first stage identifies that you do indeed have a voltage dip problem, you now have to find the source.

Move the analyser back to the origin of the supply, i.e. the point of common coupling (PCC) and monitor there. Monitor the current in each phase as well to check for increased current correlating to voltage dips (although it may be difficult to identify them at this measurement position). If the voltage dips are less frequent and have a higher retained voltage, and if there are identifiable correlated current increases, then the dips are caused by equipment in your own installation. Move forward, monitoring the voltage dips at each distribution point together with the current on each sub-circuit, and the source of the problem should be revealed. You can also take a more pragmatic approach and test circuits feeding heavy or cyclic loads first – suspect photocopiers and laser printers, lifts and hoists, heating and ventilating equipment, presses, arc furnaces…

Once you have found the problem, the solution is simple. The disturbing load must be wired directly to the PCC – lowest impedance point in the system – so that it has the least effect on voltage.

If the voltage dip performance at the PCC is similar to that at the load, then it is more likely that the source of the dips is outside your installation. Now you have the evidence to talk to your Distribution Network Operator.