Frequently Asked Questions
How Does it Work?
How does it work? In fluid dynamics Bernoulli’s principle states that an increase in the speed of air over a surface causes a decrease in pressure on that surface. A Boeing 747 that weighs 500,000 pounds takes off at about 150 mph wind speed.
What this clearly shows is that a half-million pound object of the right shape and size can be lifted by a 150 mph wind. So if low pressure created by a wind can be made to pick an object up, that same low pressure can be made to push an object down. This is the heart of the CREWSAFE design. All CREWSAFE shelters use this principle to turn the destructive force of the wind against itself to create a stabilizing force. In fact, when wind passing over a CREWSAFE shelter reaches 350 mph the downward force created gives the shelter an effective weight of over 115,000 pounds. This massive downward force coupled with the unique shelter shape and configuration is what locks the shelter to the ground and keeps it from being lifted, overturned or otherwise being moved by the wind.
How is it Anchored?
To withstand an EF-5 tornado CREWSAFE Shelters require NO anchoring. CREWSAFE’s are totally stable just sitting on any relatively flat soil, gravel, asphalt, concrete or other surface. No anchors mean no chance of a failure such as the breakage of the turnbuckle on the Cactus Rig #117.
What does it weigh?
About 25,000 pounds of steel are used to make the largest shelters.
Is it Patented?
All Red Dog Mobile Shelters, LLC, mobile shelters are covered by US Patent 8,136,303 and/or other Patents Pending as issued by the United States Patent and Trademark Office.
Has it been tested?
All critical components have passed the most severe actual missile impact tests as performed by the nationally recognized Texas Tech Wind Science and Engineering Research Center (WiSE) in LubbockTX. More Information.
Nationally recognized 3rd Party Engineering Reviewer(s) and NSSA have confirmed and officially validated the design and all calculations upon which the CREWSAFE shelter is based. A Governmental sponsored research and experimentation plan is currently being developed in association with Dr. Daan Liang, PhD, P.E. (Assistant Professor of Construction Engineering and NSSA recognized wind load expert) for full scale CREWSAFE wind testing at the WiSE Reese AFB.
How is it made?
The 30-person CREWSAFE model shelter is constructed of approx. 1″ thick A36 steel floor plates and 1/2″ thick, 4″ channel reinforced, rolled roof and walls, 10”-14″ diameter supporting columns and vacuum pipes (capable of supporting nearly 500,000 pounds roof weight), 10”x 20#/ft channels and 10”x 54#/foot wide flange beams. The 250 pound doors are ADA compliant and can easily be removed by protected occupants should the opening swing of the door be blocked following a severe weather event by heavy residual storm debris.
How strong is it?
The two internal ducting columns can each support 246,000 pounds of weight without buckling. The Cactus Rig #117 roof collapse can not happen with a CREWSAFE. Had a cactus crew member been standing under this portion of the roof it could have been fatal. CREWSAFE’s 1/2” A36 steel plate walls are rolled into a curved shape adding significantly to its strength and ability to withstand impact loads without deformation. The design is specific to a drilling rig site in recognition of the potential for heavy debris to be launched into the shelter by the extreme winds. The shelter safety capsule and connections are capable of withstanding the most forceful of blows without compromise. Lateral grousing stabilizers act as “shock absorbers” to minimize the transfer of shock loads from impacts significantly affecting the occupants
How do you know a CREWSAFE safe is safe?
According to the United States Government Federal Emergency Management Agency (FEMA) there is no such thing as an “Absolutely” safe shelter or any kind. The highest FEMA rating available for storm shelters is classified as “Near Absolute”. CREWSAFE shelters are certified to meet the highest FEMA rating level of “Near Absolute”.
How much wind can a CREWSAFE safe take?
CREWSAFE units are certified by Red Dog Mobile Shelters, LLC, to withstand wind loads 200% stronger than very other Tornado Shelter/Safe Room available on the market. CREWSAFE’s are industrial strength having been specifically designed for 350 mph winds versus the 250 design basis for other Certified residential and community storm shelters and safe rooms. Wind loads at 350 mph are twice as forceful as those at 250 mph.
How fast are the winds in an EF-5 tornado?
The tornado that completely destroyed the Cactus Rig #117 in May of 2011 in Central Oklahoma was most likely an EF-3 or weak EF-4 tornado. Winds there were most likely under 165 mph. An EF-5 tornado has winds of up to 250 mph. Since wind forces increase geometrically with wind speed an EF-5 tornado is twice as strong as the storm that destroyed Cactus #117. Scientists measured the fastest wind speed ever recorded, 318 mph, in one of the tornadoes that hit the suburbs of Oklahoma City on May 3, 1999. The second strongest likely occurred in the Greensburg KS, EF-5 in 2009 (http://www.fema.gov/library/viewRecord.do?id=3566) and these were estimated at 308 mph. CREWSAFE shelters are designed for winds speeds of over 350 mph. Wind forces at 350 mph are 4.5 times stronger than those at 165 mph and nearly 1.5 times stronger that those at 300 mph. More information about wind speeds and tornados can be found athttp://www.spc.noaa.gov/efscale/
How important is it that a Shelter be a “Certified Safe Room”?
What is the International Code Council “ICC500/NSSA Standard”?
Who is the National Storm Shelter Association (NSSA)?
What options and upgrades can I get?
Depending upon the particular model and Shelter size, there is almost no limit to the options and modifications that can be included. Options include but are not limited to:
•CREW-ALERT™ visual alarms. A rotating beacon and two flashing strobes on the Shelter are triggered anytime the NOAA (the US National Oceanographic and Atmospheric Administration) or the US Weather Bureau issue a regional tornado warning. An official “Tornado WARNING” is always based upon official radar indications and/or actual Spotter sightings and is issued for a specific geographic area. The Safe Room CREW-ALERT system “knows” where the shelter is deployed and lets the crew know when it is time to get inside.
•BUBBLE-TITE™ Venting and Sealing system. Manually operated internal valving can be closed to seal CREWSAFE-30B Shelter occupants off from H2S and other poisonous gases. Sufficient breathing air exists for the rated number of occupants to stay protected up to 90 minutes without exceeding allowable CO2 saturation levels.
•HVAC with insulation can be added for operation between -20 to +120 deg F.
•Domestic Terrorism Resistant: Penetration resistance up to Level 6 bullet-proofing is available. (Note: Standard shell of 1/2”, A36 steel is rated at Level 2 bullet-proof. See (http://www.tssbulletproof.com/bullet-resistant-barriers/bullet-proof-protectionlevels) for Underwriters Laboratory table of bulletproof performance.
•Lockers, benches, change room amenities, first aid station, wash facilities, etc. are available.
•Other options are available upon request
How many workers can it protect?
The ICC500/NSSA 2008 Standard as well as the US Dept. of Homeland Security, Federal Emergency Management Agency (FEMA 320 & 361) stipulate that a shelter must provide 5 square feet of unobstructed floor area per rated occupant. The CREWSAFE-30B has a rated occupancy of 30 persons. Although the shelter is designed for 30 persons, as many as 90 persons can safely fit inside if needed.
Will a cellphone work inside of it?
If cell phone reception is acceptable outside the Shelter it will most likely be acceptable inside. However every location has its own peculiarities. You should test phone reception as an important part of any recommended tornado drills you may conduct.
Where can I buy one?
Red Dog Mobile Shelters are not sold. As a critical component of any meaningful safety program each certified unit is installed and maintained by a Certified Installation Technician. Each shelter is assigned a serial number by NSSA and the GPS location of each shelter is constantly updated and maintained on file at NSSA headquarters in Lubbock, TX..
Where can I rent one?
To get a quote for your particular needs contact Light Tower Rentals at 432-530-3330 (www.lighttowerrentals.com)
What is included in the lease cost?
Regular cleaning, maintenance, upkeep, light replacements, electronic and mechanical testing are part of each deployment and subsequent move. Moving costs are extra and are based upon standard rates for time and distances involved.
Who moves the shelters to new locations when needed?
One call does it all. When it is time for a shelter to be moved to a new location one call to Light Tower Rentals at 432-530-3330 gets it done.
What does it cost?
Lease costs depend upon a variety of factors. To get a quote for your particular needs contact Light Tower Rentals at 432-530-3330 (www.lighttowerrentals.com) but here are some “rules of thumb”:
- • The longer the lease period, the lower the lease cost
- • The more units a customer leases, the lower the per unit cost
- • The fewer the options added and the fewer amenities wanted, the lower the cost.Safe Room FAQs provided by Red Dog Mobile Shelters.