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Author Message Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 915 Registered: 01-2003 Posted on Thursday, June 09, 2016 - 02:49 pm:    MasterSpec users probably use lbf (pounds force) instead of lb (pounds) in their specs. How common is lbf in specifications for non-MasterSpec users? How common is lbf on drawings? The specs might use lbf, but lb might be used on drawings. user (Unregistered Guest) Unregistered guest Posted on Thursday, June 09, 2016 - 03:13 pm:    Use lbf in specifications, not lb. Dewayne Dean Senior Member Username: ddean Post Number: 55 Registered: 02-2016 Posted on Thursday, June 09, 2016 - 03:51 pm:    Spec Link uses lbf in a few places. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 157 Registered: 10-2003 Posted on Thursday, June 09, 2016 - 05:18 pm:    Forgive me for being "sluggish", but would someone explain: 1. If we are building static structures on earth, why and where would we use lbf instead of lb mass? 2. How did I make it through architecture school and 35+ years of architectural practice and never heard of lbf? Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru George A. Everding, FCSI, CCS, CCCA, AIA Senior Member Username: geverding Post Number: 828 Registered: 11-2004 Posted on Thursday, June 09, 2016 - 05:39 pm:    Nice pun, Michael. One lbf accelerates one slug by 1 ft/s^2, for those who have forgotten what they learned in high school. Dave Metzger Senior Member Username: davemetzger Post Number: 644 Registered: 07-2001 Posted on Thursday, June 09, 2016 - 05:45 pm:    That must have been an advanced high school you went to, George. I don't remember learning that in college--though that's probably more a reflection of my porous mind than of what were the pretty good structures courses I took at Michigan. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1649 Registered: 05-2003 Posted on Thursday, June 09, 2016 - 06:38 pm:    Michael, look at ASTM E 985 or the building code for railing design, its been referenced in ever railing spec I prepare, typically calling for Uniform Load of 50 lbs/ft applied in any direction,on top rail of railing system. Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1405 Registered: 03-2003 Posted on Thursday, June 09, 2016 - 06:57 pm:    Ah, the benefits of the metric system. When one uses "pound" we don't know if they're talking about mass, force, or English currency. But with the metric system it is clear: * gram = mass * Newton = force * pound = that funny money over the pond. Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 158 Registered: 10-2003 Posted on Thursday, June 09, 2016 - 07:51 pm:    Jerome As you point out, the required load resistance on railings is described as pounds (lb), not as pound force (lbf). It is generally understood that the load on the rail is a force, not a mass. But sometimes a railing is tested in a horizontal position by applying a mass. So my question remains -- is using lbf in specifications meaningful to the typical designer and builder or jury? Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 159 Registered: 10-2003 Posted on Thursday, June 09, 2016 - 07:57 pm:    Ron There is much to recommend about SI, but lexiconic purity is not one of them. A gram is also a category of legume, and a Gram is a characteristic of cell physiology. Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 916 Registered: 01-2003 Posted on Friday, June 10, 2016 - 03:39 pm:    Good question (and pun), Micahel. One could argue that pounds-force or lbf are the "correct" term, as used by physcists and engineers, and it would be hard to reject that argument. Practically speaking, I doubt anyone has ever been confused by the use of pounds or lb whether used for mass or force. My old specs did not differentiate, and we never had a problem because of the units. BSD uses pounds, pounds-force, pounds-force/inch, pounds per square inch, psi, lbf/in, lbf/sq ft, and lbs for pressure. For weight and density, it uses pounds, lb, and lbs. I'm sure neither MasterSpec nor SpecLink users change whatever units are in the specifications, so pounds-force and similar units are being used. The reason the question came up is that we're updating our drawing notes, which include lb as an abbreviation for pound and pounds. As noted above, that sometimes agrees with what's in SpecLink - and sometimes does not, which makes it hard to decide what to do with the drawing notes. By the way, lbs is not a valid abbreviation. I think we'll go with lb regardless of application. Now if only there were a way to to a global search and destroy on the specs... Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 174 Registered: 10-2003 Posted on Monday, July 11, 2016 - 06:27 pm:    For the first time, I saw lbf used in a non-technical document. The tire inflation pressure is stated in lbf in the Toyota Prius User Manual. It is still confusing to me, but at least I am now attuned to noticing. Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru