Tips for Building
104 l/min delivered at 7 bar and 87 dB(A) guaranteed sound power: the HC51Si is the only machine in the panel that pairs strong delivery with restrained noise. It pays for it in weight, 29 kg.
What its figures are worth
- Air delivered at 7 bar 40 %104 l/min · 8/10
- Price per delivered l/min 25 %2.8 USD per l/min · 6.5/10
- Sound power LwA 20 %87 dB(A) · 7.5/10
- Weight 15 %29.2 kg · 6.5/10
Every criterion in the scale could be calculated. Weighting: Air delivered at 7 bar 40 %, Price per delivered l/min 25 %, Sound power LwA 20 %, Weight 15 %.
Choose it if
- Working in a garage or next to an occupied house.
- Spray painting or firing nails through a long session.
- A delivery curve published in full, from 1 to 8 bar.
Skip it if
- Carrying it: 29.2 kg, the second heaviest.
- Pressure: 8 bar maximum, against 10 for several rivals.
Published specifications
| Specification | Stated value |
|---|---|
| Air delivered at 7 bar | 104 l/min |
| Air intake | 300 l/min |
| Maximum pressure | 8 bar |
| Tank | 50 L |
| Motor | 1,500 W |
| Pump | Oil-free, twin cylinder |
| Sound power LwA | 87 dB(A) |
| Sound pressure | 60 dB(A) at 7 m and 25% load |
| Weight | 29.2 kg (net) |
Before you connect the first tool
- Never point the blow gun at skin. Not to dust off clothes you are wearing, not as a joke. Compressed air can enter the skin and cause a serious injury.
- Eye and hearing protection. A blow gun throws chips and dust at eye level, and most of these machines exceed 90 dB(A) of sound power.
- The tool's pressure, not the tank's. Set the regulator to the pressure stated on the tool. Never adjust the pressure switch or the safety valve.
- Drain the tank. Condensed water collects at the bottom and corrodes the steel from inside. Open the drain valve after use, with the tank depressurised as the manual describes.
- A long hose rather than a long extension lead. A lead that is too long or too thin drops the voltage when the motor starts. Manuals advise bringing the compressor close to the socket and running a longer air hose.
What the maker shows
Frequently asked questions
Where does this machine's score come from?
It is calculated, not awarded. Five measurable criteria are weighted, and each value is mapped onto a scale relative to the other machines in the comparison. For this machine, 100% of the scale could be applied: criteria the maker does not publish drop out rather than being replaced by an estimate.
Which tank size, 24 or 50 litres?
The tank is a reserve, it does not increase air delivery. A 24 litre machine is enough for a nailer, a blow gun and inflating, and it is easy to store and carry. A 50 litre tank lets the motor rest longer between cycles, which matters for spray painting or long sessions.
Oil-free or oil-lubricated?
An oil-free compressor needs no oil changes and can lie flat in a car boot. An oil-lubricated one needs its oil level checked and travels upright. In this comparison, only the Scheppach HC26 is lubricated.