FAQ: Compressors

Blackmer FAQ: Compressors

• How often should you change the oil for compressors?

  For Blackmer Reciprocating Gas Compressors the oil should be changed every 1,000 hours of operation, or every six months whichever occurs first. If the oil becomes dirty or diluted, change oil and external filter as often as needed to maintain clean oil.

• Are Blackmer Reciprocating Gas Compressors Bi-directional?

  Yes, Blackmer Reciprocating Gas Compressors are bi-directional. Blackmer changed the design of the oil pump to a bi-directional design, allowing the gas compressor to run in either direction.

• What is the service schedule for a Blackmer Reciprocating Gas Compressor?

  

• Do I need a strainer? What strainer size I should use with a Blackmer Reciprocating Gas Compressor?

  Yes, you should install a strainer in the inlet line to protect the gas compressor from foreign particles. A strainer of mesh size 30 or finer is recommended. Clean the strainer every 180 days or more frequently, if the system requires.

• What gases can a Blackmer Reciprocating Gas Compressor handle?

  Blackmer reciprocating gas compressors can handle almost all different gases except a few exceptions like acetylene or oxygen (oxygen due to special cleaning requirements). Our line of NGS Series Reciprocating Gas Compressors can even handle 8% H2S. Please contact Blackmer if you have any special gas handling requirements.
  
  - LB Series Gas Compressors - Propane, butane, and anhydrous ammonia
  - HD Series Gas Compressors - Wide range of industrial gases
  - NG Series Gas Compressors - Natural gas, sour gas, and methane gas mixes

• What is the difference between different mountings?

  Blackmer provides different mountings for our reciprocating gas compressors. Below are the available mounting options:

  • CO – Compressor only, where we provide just a bare shaft compressor with flywheel.
  • B – Base mounting, where the compressor is mounted on a base plate with drive components. Blackmer can also provide the compressor unit with a motor.
  • TU – Transfer unit, includes what is provided in the 'B' mounting plus a small inlet liquid trap (non-ASME) with mechanical float (option to install a float switch) and drain valve, and NPT interconnecting piping from trap to the compressor. 
  • TC – Transfer unit, similar as TU unit but comes with a large ASME coded liquid trap instead of non-ASME trap and the option to install two float switches instead of mechanical float. This unit also includes NPT relief valve on the liquid trap.
  • TW – Transfer unit, similar as TC unit but comes with large ASME trap with flange connections and all interconnected piping is welded and flanged (except for the instruments connection ports). TW units are mounted on structural steel base. This unit also includes flanged relief & drain valve on the liquid trap.
  • LU – Liquid transfer and vapor recovery unit, similar as TU unit with the addition of a 4-way valve, interconnecting piping, and an inlet strainer. 
  • LC – Liquid transfer and  vapor recovery unit, similar as LU unit but includes a large ASME coded liquid trap instead of non-ASME trap and the option to install two float switches instead of mechanical float. This unit also includes NPT relief and drain valve on the liquid trap.
  • LW – Liquid transfer and vapor recovery unit, similar to a LC unit but instead of NPT interconnecting piping, LW mounting comes with all welded and flanged piping connections (except for the instruments connection ports). This unit also includes flanged relief and drain valve on the liquid trap. LW units are mounted on structural steel base. This unit does not includes an inlet strainer.

• Why should I use a gas compressor for LPG transfer instead of a sliding vane pump?

  There are many reasons that LB Series Gas Compressor would be a better and more profitable choice for LPG transfer instead of a sliding vane pump:

  • Sliding vane pumps transfer fluids and not vapors. Leftover vapors in tanks is approximately equal to 3% of the tank volume. With a gas compressor you can transfer most of these vapors plus the liquid heel (liquid below tank dip tube which you cannot take out with the pump) gaining almost 3% of the tank capacity fluid. By capturing all the fluids and vapors in the tank means additional profits for your operation.

  • Top opening tanks like railcars (most rail cars have top opening) results in poor suction conditions for the pump which results is shorter pump components life while compressor can handle it easily.
  • There are tanks which does not have any liquid opening like domestic cylinders or tank cars involved in an accident may not have liquid opening accessible and in such cases where pump cannot be used while compressor can easily unload these tanks.

  Please review following link for more information.

• What does the last letter in the gas compressor model represents? For example, I have two compressors model, one is a HD362B and the other is HD362C.

  The last letter in the compressor model represents design revision level. For example, HD362C is the current version of the HD362 machine where ‘C’ represents current version of this HD362 machine. While HD362B was the older ‘B’ version.

• I have 4,000 gallon capacity propane tank and I want to unload liquid in ten minutes? Can I use a compressor for it?

  You will not be able to unload liquid from such a small tank in such short time due to excess flow valve installed on the tank and piping system. As soon as the compressor starts, the excess flow valve on your tank will shut off automatically as it will not be capable to transfer 400 gpm (1,514 L/min) of liquid (this is not a compressor limitation but your system limitation). Typically for such a small tank, you will need smaller compressor depending on piping system and excess flow valve on the tank, which will work fine but it will not finish the job in ten minutes. Typically, following machines are suitable different size of tanks:

  - 4,000 gallons (15,141 L) capacity tank - LB081/2
  - 11,000 gallons (41,640 L) capacity tank - LB161/2
  - 26,000 gallons (98,421 L) capacity tank - LB361/2
  - 33,000 gallons (124,919 L) capacity tank – LB601/2
  - Larger tank like ship or barge or multiple railcars - LB942