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Valves contribute to safety by allowing you to shut off the supply of liquid or gas in the event that the hose assembly or attachment should fail. Central States Hose stocks a variety of popular valves including ball valves and gate valves available in brass, stainless steel or polypropylene. A "Banjo" brand ball valve made of polypropylene is pictured here. (for the Banjo liquid handling products catalog, visit www.banjocorp.com)

Safety Factors

Boston hoses are manufactured and tested considering maximum surge pressure as the limit for working pressure. In other words, any pressure surges, spikes, or jumps cannot exceed that of the hose's maximum working pressure. Failure to select a hose that meets this criteria could lead to end blow-offs, hose leakage, and hose bursts. The result could be serious injury, death, or equipment damage.

Boston employs a 4:1 (burst:working) SAFETY FACTOR to a Chemical, Air, or Water hose's burst pressure to ensure the customer's safety. This means that the burst pressure is a minimum of four times greater than the working pressure. Additionally, it may be reassuring to know that every length of Boston chemical transfer hose is pressure tested to 1-1/2 times its working pressure before it is packaged and shipped!

Boston employs a 10:1 (burst:working) SAFETY FACTOR to a Steam hose's burst pressure. This means that the burst pressure is a minimum of ten times greater than the working pressure.

A few hoses deviate from these safety factors, including:

Contractors Water

3:1 Safety Factor

Green Garden

3:1 Safety Factor

Leader Water Discharge (Light Duty)

3:1 Safety Factor for product codes 43-0307-XX-XXXX.

Bend Radius

The bend radius is the radius to which the hose can be bent in service without damage or shortening its life. Textile reinforced hoses have a tendency to kink as the bend radius is reduced. A helical wire is used inside the hose layers to help withstand severe bends without flattening or kinking.

General Formula to Determine the Bend Length

[(Angle of Bend)x(2)x(Pi)x(r)]/360°=minimum length of hose to make bend

Pi=3.14

r=given bend radius of hose

Example: To make a 180° bend with Puma Tank Truck hose of 2" I.D.

Bend Radius of Puma=6"

Therefore, [(180°)x(2)x(3.14)x(6")]/360°=18.84". This formula does not mean 18.84" will be long enough to meet the application need. It only means that if the 180° bend takes place in less than 18.84" the flow of fluid or material could be restricted or the hose could be damaged.

Important! The minimum bend radius is measured to the inside of the curvature.

Remember that the bend should be smooth and should take place over the entire minimum length.

A list of chemicals and hose compatabilities is available from a Boston Distributor. It is imperative that this list is used as a "guide" only. The degree of resistance of any elastomer with a particular fluid depends upon such variables as temperature, concentration, pressure conditions, velocity of flow, duration of exposure, aeration, stability of flow, coupling compatability, etc. Therefore, if doubt exists, it is not advisable to use the hose until verification is provided by a Boston specialist. If this is not practical, testing should be devised to simulate as realistically as possible the same service conditions and evaluate the hose's performance.

WARNING: A failure of chemical hose in service can result in injury to personnel or damage to property. All chemical hose manufacturers recommend specific hose constructions to handle various chemicals. THE MANUFACTURER SHALL BE CONSULTED TO DETERMINE WHAT PARTICULAR HOSE MAY BE USED TO HANDLE A SPECIFIC CHEMICAL.
WARNING: Do not use chemical hose at temperatures of pressures above those recommended by the manufacturer. All operators must be thoroughly trained in the care and use of this hose and must at all times wear protective clothing. A hose or system failure could cause the release of a poisonous, corrosive, or flammable material.

Steam Hoses

WARNING: Exposure to steam is hazardous! If not properly controlled, steam can cause serious bodily injury or death and property damage. Steam hoses must be properly selected, coupled, tested, installed, used, and maintained.

Steam Hose Failure Analysis provides methodology for determining the status of a steam hose.

A Saturated Steam Temperature table provides saturated steam (not super-heated!) temperatures corresponding to steam pressures.

Proper hose selection includes:

• selecting a hose identified as steam hose construction,
• providing steam hose identification in the form of permanent branding on the hose's outer cover, not just the package,
• identification of the type of service the steam hose is to accomplish,
  • Is the hose manually handled?
  • What is the anticipated frquency of use?
  • What is the actual pressure of the steam service?
  • Is the hose subject to pressure surges or peaks?
  • What is the temperature of the steam?
  • Is the steam saturated (wet) or super-heated (dry)?
  • What environmental factors may the hose cover be exposed to?
• and recognizing potential spillage or accumulations of corrosive or petroleum-based products may have deteriorative effects on a hose cover.

Ensure that the hose is properly installed:

• Use hose couplings designed for steam service. Steam hose couplings use a bolt-on outside clamp which can be re-tightened over the hose's service life.
• Avoid extreme hose flexing near the coupling. Use elbows in the piping system to assure a straight line connection with the hose.
• Installation of a shut-off valve between the steam source and hose will maximize hose service life and operator safety. Boston considers a shut-off valve mandatory!
• Spring guards can relieve some of the acute flexing encountered in heavy manual handling applications.
• Provide a suitable means of storing the hose when not in use. A permanent rack or tray will minimize damage to the hose while in storage. Do not hang the hose on a hook, nail, or other object which could cut or damage the hose.

Common Sense with Steam equals Safety:

• Provide operators with adequate safety clothing including gloves, rubber boots, full-length protective clothing, and eye protection. This minimizes the effects of scalding burns received from splash-back of steam or hot water.
• Ensure the working area is clear of clutter and tripping hazards.
• Check the tightness of coupling bolts prior to each use.
• De-pressurize the hose after use. This provides safety and dramatically increases hose life.
• The best prevention of accidents is an awareness and anticipation that they may occur.

Preventive, Periodic Maintenance Pays Off
All hoses wear eventually wear out. It is important to be mindful of and on the look-out for the hose that has deteriorated to the point where it can no longer provide safe service.

What to look for in a hose near the end of its useful life:

• cover blisters or lumps.
• cuts or gouges in the hose cover that expose the reinforcement.
• steam leaks at the coupling ends or anywhere along the length of the hose.
• flattened or kinked areas which have damaged the hose.
• a reduction in steam flow indicating that the tube is swelling.

When any of these conditions occur, it is good safety sense to immediately remove the hose from service. Once removed, the hose can be carefully inspected before further use.

Often times a steam hose failure will occur near the ends due to flexing and strain at the coupling. In such instances, the hose can be cut back and recoupled, providing additional service life. Hoses used in continuous high pressure/temperature service should be periodically inspected for signs of tube hardening. Generally speaking, it is necessary to remove the coupling for tube inspection.