A blade holding device for securely holding a saw blade includes a holding unit, a sleeve member, a retaining unit, and a shell. The holding unit includes a clamp member and an insert. The clamp member has two half portions defining a gap for receiving the saw blade, a slot extending through one of the half portions, and an abutment surface. The insert is inserted into the slot, abuts against the abutment surface, and has a threaded hole. The sleeve member surrounds the half portions of the clamp member without blocking the threaded hole. The retaining unit includes a fastening member extending threadedly through the threaded hole for pressing against the saw blade. The shell surrounds the sleeve member and the clamp member.

A pneumatically powered pole saw is provided, the pole saw having gas actuated main valves configured for movement between first positions and second positions wherein the gas actuated main valves are located in a main valves assembly fluidly coupled to the piston chamber; and a first pilot valve is configured to send actuating gas through a conduit to the main valves assembly and a second pilot valve is configured to send actuating gas through a conduit to the main valves assembly wherein the cutting blade moves in opposite directions in response to the actuating gas of the first and second pilot valves.

A pneumatically powered pole saw is provided, the pole saw having gas actuated main valves configured for movement between first positions and second positions wherein the gas actuated main valves are located in a main valves assembly fluidly coupled to the piston chamber; and a first pilot valve is configured to send actuating gas through a conduit to the main valves assembly and a second pilot valve is configured to send actuating gas through a conduit to the main valves assembly wherein the cutting blade moves in opposite directions in response to the actuating gas of the first and second pilot valves.

A remote manufacturing yard configured to build a cryogenic distillation column for use in an air separation unit (ASU) is provided. the remote manufacturing yard can include a fabrication facility comprising an enclosure. The fabrication facility further can also include a vertical plate roller; a lifting device, an assembly table configured to support two or more partial shells simultaneously; a first weld machine configured to weld the two or more partial shells together to form a course while keeping the two or more partial shells stationary; a column section assembly area having a second weld machine disposed therein, a distributor installation area configured to receive at least one column section and install a distributor within the column section to form a distributor column section; and a packing installation area configured to receive the distributor column section and install packing within the distributor column section to form a packed column section.

A pneumatic valve assembly with a trigger for switching the pneumatic valve assembly between two or more valve operation modes is disclosed herein. The valve operational modes are determined by selection of fluid conduits by a trigger valve assembly of the pneumatic valve assembly which interconnects fluid conduits to a main valve, pilot valves and a pneumatic cylinder of a fluid powered pole saw and wherein a piston located in the pneumatic cylinder is mechanically coupled to a cutting blade of the pole saw and the trigger is operatively coupled to the trigger valve assembly, wherein the pneumatic valve assembly is axially aligned with pneumatic cylinder.

A pneumatic valve assembly with a trigger for switching the pneumatic valve assembly between two or more valve operation modes is disclosed herein. The valve operational modes are determined by selection of fluid conduits by a trigger valve assembly of the pneumatic valve assembly which interconnects fluid conduits to a main valve, pilot valves and a pneumatic cylinder of a fluid powered pole saw and wherein a piston located in the pneumatic cylinder is mechanically coupled to a cutting blade of the pole saw and the trigger is operatively coupled to the trigger valve assembly, wherein the pneumatic valve assembly is axially aligned with pneumatic cylinder.

A pneumatic device includes a cylinder, a piston rod and a valve unit. The cylinder includes an air chamber in which the piston rod is mounted, and a plurality of first backward flow paths. The valve unit is connected to the cylinder, and includes a valve seat assembly, and a valve member. The valve seat assembly includes an intake passage, a plurality of forward flow paths and a plurality of second backward flow paths. The valve member is movable between a first position where fluid communication between the intake passage and each of the second backward flow paths is prevented, and a second position where fluid communication between each of the forward flow paths and the communicating hole is prevented.

A blade holding device for securely holding a saw blade includes a holding unit, a sleeve member, a retaining unit, and a shell. The holding unit includes a clamp member and an insert. The clamp member has two half portions defining a gap for receiving the saw blade, a slot extending through one of the half portions, and an abutment surface. The insert is inserted into the slot, abuts against the abutment surface, and has a threaded hole. The sleeve member surrounds the half portions of the clamp member without blocking the threaded hole. The retaining unit includes a fastening member extending threadedly through the threaded hole for pressing against the saw blade. The shell surrounds the sleeve member and the clamp member.

A blade holding device for securely holding a saw blade includes a holding unit, a sleeve member, a retaining unit, and a shell. The holding unit includes a clamp member and an insert. The clamp member has two half portions defining a gap for receiving the saw blade, a slot extending through one of the half portions, and an abutment surface. The insert is inserted into the slot, abuts against the abutment surface, and has a threaded hole. The sleeve member surrounds the half portions of the clamp member without blocking the threaded hole. The retaining unit includes a fastening member extending threadedly through the threaded hole for pressing against the saw blade. The shell surrounds the sleeve member and the clamp member.

A pneumatic saw includes a housing, a piston casing, a piston, and an air guide assembly. The air guide assembly is in the housing, and includes a reversing brake block, an air guide base, a spacer plate on the air guide base, and an air blocking ring on the air guide base. The air guide base includes an air inlet duct for accommodating the reversing brake block, and primary working air ducts communicated with the air inlet duct, and secondary working air ducts communicated with the air inlet duct. The primary and secondary working air ducts respectively includes a longitudinal hole parallel to the air inlet duct, and a transverse through hole communicated with the air inlet duct and the longitudinal hole. The transverse through hole is shielded by the air blocking ring, and the air blocking ring is fixed to the air guide base by a pin member.