Flow Rate & Pressure

Flow Rate

In traditional pipe fittings, such as press or push-fit, the connection with the pipe reduces the internal bore. This negatively impacts the flow rate at which the fluid passes through the system, increasing the likelihood of pressure drops.

Aquatechnik’s jointing method is not like that of traditional systems. The method adopts a unique flaring tool which expands the pipe bore. This wider bore gives the Safety-Plus system excellent advantages over traditional systems, helping to maximise flow rates, reduce noise and save energy when operating at the same pressure rate.

A wider pipe bore is also significantly less likely to suffer from the formation of deposits (such as limescale) that typically affect the operating conditions of a system. Pressure drops caused by these deposits can force pumps to operate at higher rotation speeds, resulting in higher energy consumption.

Our multi-layer pipe’s internal surface has minimal roughness and offers low resistance to hot and cold fluid flow. This makes the Safety-Plus system less prone to forming deposits, which reduces flow rates over time.

These factors allow higher water speeds in distribution networks without the negative consequences that can arise in metal pipes (turbulence, noise, flow rate reduction and erosion).

Pressure

Pressure drops are often caused by resistances that oppose the fluid motion, which may be continuous or localised. Continuous drops occur along linear sections of a system. In contrast localised drops are accidental and vary the direction or the cross-section of fluid flow (e.g., reducers, branches, Tee, elbows, influxes, valves, filters, etc.)

The inner and outer layers of the multi-layer pipe are manufactured from cross-linked polythene (PE-Xb), a polymer used in engineering installations for over thirty years that has a resistance to high temperatures and elevated hydrostatic pressures. As far as organoleptic and non-toxicity factors are concerned, this material is universally recognised as one of the most suitable for conveying drinking water.

Unlike other processes, such as overlapping, our method of moulding aluminium pipes guarantees uniformity of thickness over the entire circumference, including the welding area. This method also ensures greater resistance to pressure, uniform mechanical properties, greater adhesion with the bonding layers and an oxygen barrier.

In accordance with the international EN ISO 21003 standard, there are four application classes or fields of use which must be checked by laboratory testing in combination with the operating pressure (PD) that the manufacturer has established (4, 6, 8, 10 bar). From this standard, multi-layer pipes are certified for all four application classes for pressures up to 10 bar, as shown in the table.

The maximum pressure the material can withstand at a constant temperature of 20°C over fifty years is determined by internal pressure resistance tests performed on pipes for over 10,000 hours (greater than a year) according to the ISO 9080/DIN 16788 standard. Testing is carried out at different temperatures to accelerate creep behaviour, subjecting the samples to various pressures and evaluating the time required to break the pipe. The values shown in the following graph are extrapolated from test report No. B477/14 was performed by IMA Dresden, an organisation accredited by DVGW, DIN CERTCO, DIBt and ISO 17025. These curves allow the determination of the operating conditions (pressures and temperatures) related to the product’s expected lifetime.

Calculation of continuation pressure drops

r = unitary continuous pressure drop (mbar/m)

Fa = dimensionless friction factor

r = density of water (Kg/m3 )

v = average water speed (m/s)

D = internal pipe diameter (m)

Please note the diameter of the pipe, the speed of the water and its density. The only parameter that is undetermined is the friction factor (Fa), which depends on the fluid flow rate and the pipe roughness.

Calculation of localised pressure drops