TNAG-1613-FCO40-2221-Executive-Council-of-Hong-Kong-memoranda-and-minutes-of-meet-1987 — Page 244

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"double acting hammer" means a device which imparts a percussive force to a pile by means of the direct or indirect impact of a piston in a cylinder falling under the force of gravity with an additional downward force being exerted by means of the injection of air or

steam at high pressure into

into the cylinder above the piston, the piston being raised by means of the injection of air or steam at high pressure into the cylinder the piston;

"drop hammer" means a device which imparts a percussive force to a pile by means of the direct or indirect impact of a mass falling under the force of gravity alone, the mass being raised by means of a

crane or winch;

"internal drop hammer" means a drop hammer used in such a manner that

the point of impact is at or near the bottom of the pile casing, the pile being a hollow steel tube or casing within which the action of the hammer takes place;

"Ordinance" means the Noise Control Ordinance;

"percussive piling" means the sinking or driving of a pile by direct or

indirect hammering or other percussive means;

"pile" has the same meaning as in the Ordinance;

"piling" has the same meaning as in the Ordinance;

"piling zone" means an area within which percussive piling may take

place, as specified in a Construction Noise Permit; and

"single acting hammer" means a device which imparts a percussive

force

to a pile by means of the direct or indirect impact of a ram falling under the force of gravity alone, the ram being raised by means of a force imparted by air or steam at high pressure.

Standard

acoustical

terminology is used throughout this Technical

Memorandum. Other terms are as defined in the Ordinance or in the text

of this Technical Memorandum.